Image copyright AP 
 
 Nigeria's police have offered a $300,000 (£180,000) reward to anyone who can help locate and rescue more than 200 abducted schoolgirls. 
 
 They were kidnapped more than three weeks ago by Islamist Boko Haram militants from their boarding school in the north-eastern state of Borno. 
 
 The militants have been blamed for another attack on a town in the state on Monday, a busy market day. 
 
 A senator from the remote area said some 300 people had died in the raid. 
 
 Ahmed Zanna said the gunmen arrived in a convoy of vans in Gamboru Ngala, near the border with Cameroon. 
 
 They stole food and motorbikes, burning hundreds of cars and buildings during their rampage, the politician told the BBC's Hausa service. 
 
 Media playback is unsupported on your device Media caption Pakistani schoolgirl Malala Yousafzai: "If we remain silent this will spread" 
 
 Mr Zanna and several residents said the gunmen had used a diversionary tactic to get the security forces out of Gamboru Ngala by spreading rumours that the abducted schoolgirls had been spotted somewhere else. 
 
 The security forces then left, leaving residents at the mercy of the attackers, they said. 
 
 Boko Haram's leader admitted earlier this week that his fighters had abducted the girls from their school in the town of Chibok on 14 April. 
 
 Abubakar Shekau threatened to "sell" the students, saying they should not have been in school in the first place, but rather should get married. 
 
 Image copyright AFP Image caption Boko Haram's leader has threatened to "sell" the students 
 
 Image copyright AP Image caption For the past week there have been daily protests countrywide calling for more to be done to find the girls 
 
 The group, whose name means "Western education is forbidden" in the local Hausa language, began its insurgency in 2009. 
 
 Global campaign The man behind the hashtag #BringBackOurGirls echoes that sentiment. "What's important is that the hashtag is raising awareness," Abdullahi told BBC Trending. "The intention of all who tweeted it was to bring this barbaric act to the attention of the world and to rescue the girls, as the hashtag says #BringBackOurGirls." First of a million tweets 
 
 An estimated 1,000 people have died in the violence and security crackdown this year alone. 
 
 A statement from the police said the 50m naira reward would be given to anyone who "volunteers credible information that will lead to the location and rescue of the female students". 
 
 Six telephone numbers are provided, calling on the general public to be "part of the solution to the present security challenge" and promising confidentiality. 
 
 Another 11 girls were kidnapped on Sunday night after two villages were attacked near the militants' forest hideout. 
 
 The abductions have prompted widespread criticism of the Nigerian government and demonstrations countrywide. 
 
 Media playback is unsupported on your device Media caption Former UN chief Kofi Annan says security forces should be used to free the kidnapped girls 
 
 The BBC's Mansur Liman in the capital, Abuja, says many are questioning why it has taken so long for such a reward to be offered. 
 
 The girls are mostly aged between 16 and 18 and were taking their final year exams. 
 
 The governments of Chad and Cameroon have denied suggestions that the abducted girls may have already been smuggled over Nigeria's porous borders into their territory. 
 
 'Mass burials' 
 
 A resident of Gamboru Ngala told the BBC 310 people had been buried on Tuesday and Wednesday, following Monday's attack. 
 
 "At the big cemetery of Gamboru Ngala, I recorded 165 buried. At the small graveyard, I recorded 145 graves. But we are still picking corpses from the main market. Many people locked themselves up in the market when the attacks started so they got burnt in their shops," he said. 
 
 Media playback is unsupported on your device Media caption Boko Haram means "Western education is forbidden" in Hausa 
 
 The militants had locked up whole families in their homes, and then would enter and spray them with bullets, another resident said. 
 
 The gunmen were shouting "Allahu Akbar [God is great]", as they stormed the remote town in Borno state, the resident added. 
 
 Correspondents say it often takes time for news of such attacks to spread as mobile phone networks can be affected by the security crackdown in the region. 
 
 On Tuesday, US President Barack Obama said he hoped the kidnapping might galvanise the international community to take action against Boko Haram. 
 
 The US has despatched a team of experts to Nigeria. 
 
 On Thursday, the UK said it was also sending a small team to provide the government with planning and co-ordination advice. The team should be on the ground within days. 
 
 Security has been tightened for the World Economic Forum for Africa, in Abuja, where two recent attacks have been blamed on Boko Haram. ||||| Story highlights China offers satellite and intelligence assistance in the search for girls 
 
 Boko Haram militants attacked Gamboru Ngala, killing at least 150 people 
 
 United States and Britain are sending teams to help Nigerian forces 
 
 Nigerian authorities offer a reward for information leading to the girls' rescue 
 
 Boko Haram launched a grisly attack on a Nigerian village in an area that troops had been using as a base in the search for hundreds of schoolgirls abducted by the militant group, witnesses told CNN on Wednesday. 
 
 The hourslong assault on Gamboru Ngala that left at least 150 people dead, some of whom were burned alive, is the latest in a series of brazen attacks and abductions by Boko Haram, raising concern about whether the Nigerian government can retake control of the region from the entrenched terror group. 
 
 Word of the attack follows news that President Goodluck Jonathan, who has been under fire for his handling of the mass abduction, accepted U.S., British and Chinese offers of assistance to find the schoolgirls, officials with those governments said. 
 
 It's unclear what impact the latest attack could have on the international response to Nigeria's fight with Boko Haram, which so far has concentrated on helping the government rescue 276 schoolgirls abducted on April 14. 
 
 The assault on the village came after military troops deployed to the area were called to the border area near Chad, where reports -- later determined to be false -- surfaced that the schoolgirls had been found with Boko Haram militants, witnesses and local officials said. 
 
 CNN cannot independently confirm the report, and attempts Wednesday to contact Nigeria's military for comment were unsuccessful. 
 
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 Indiscriminate killing 
 
 Witnesses described a well-coordinated attack that began shortly after 1:30 p.m. local time Monday at a busy outdoor market in Gamboru Ngala. 
 
 Wearing military uniforms, the militants arrived with three armored personnel carriers, they said. 
 
 They shouted "Allahu Akbar" -- "God is great" -- and opened up on the market, firing rocket-propelled grenades and tossing improvised explosive devices, witnesses said. 
 
 Some marketgoers tried to take shelter in shops only to be burned alive when the gunmen set fire to a number of the businesses, the witnesses said. 
 
 A few Nigerian soldiers who had been left behind at the village could not hold off the assault and were forced to flee, they said. Many sought safe haven in nearby Cameroon, they said. 
 
 The fighters also attacked the police station during the 12-hour assault, initially facing stiff resistance. They eventually used explosives to blow the roof off the building, witnesses said. Fourteen police officers were found dead inside, they said. 
 
 The final death toll could be closer to 300, Nigerian Sen. Ahmed Zanna told CNN. 
 
 Monday's bloody attack by Boko Haram militants, some of whom U.S. officials say have been trained by al Qaeda, follows a pattern of seeking revenge against anybody who is perceived to have provided aid to the Nigerian government. 
 
 International aid taking shape 
 
 News of the attack came as U.S. officials pressed ahead with plans to provide Nigeria with law enforcement assistance and military consultations, State Department spokeswoman Jen Psaki said. 
 
 "Obviously, this is in the interest of the Nigerian government to accept every aspect of our assistance," she told reporters during a briefing Wednesday. "They conveyed that they were willing to do that yesterday and it continues to be in their interest to be as cooperative as possible." 
 
 U.S. officials will establish a joint coordination cell at the U.S. Embassy in Abuja where the goal will be to provide intelligence, investigations and hostage negotiation expertise, Psaki said. The cell will include U.S. military personnel, who are expected to arrive in Nigeria in the coming days, she said. 
 
 The Pentagon has started planning for how it can help Nigeria, a senior U.S. military official told CNN. It's unlikely at this point that U.S. troops would be involved in operations, the officials said. 
 
 Map: Where the girls were kidnapped 
 
 Photos: Photos: Nigerians protest over kidnapped girls Photos: Photos: Nigerians protest over kidnapped girls Nigerians protest over kidnapped schoolgirls – Police in riot gear block a route in Abuja, Nigeria, on Tuesday, October 14, during a demonstration calling on the Nigerian government to rescue schoolgirls kidnapped by the Islamist militant group Boko Haram. In April, more than 200 girls were abducted from their boarding school in northeastern Nigeria, officials and witnesses said. Hide Caption 1 of 19 Photos: Photos: Nigerians protest over kidnapped girls Nigerians protest over kidnapped schoolgirls – Women in Abuja hold a candlelight vigil on Wednesday, May 14, one month after the schoolgirls were kidnapped. Hide Caption 2 of 19 Photos: Photos: Nigerians protest over kidnapped girls Nigerians protest over kidnapped schoolgirls – People march in Lagos, Nigeria, on Monday, May 12, to demand the release of the kidnapped schoolgirls. Hide Caption 3 of 19 Photos: Photos: Nigerians protest over kidnapped girls Nigerians protest over kidnapped schoolgirls – Catholic faithful in Abuja take Holy Communion and pray for the safety of the kidnapped schoolgirls on Sunday, May 11. Hide Caption 4 of 19 Photos: Photos: Nigerians protest over kidnapped girls Nigerians protest over kidnapped schoolgirls – Catholic faithful attend a morning Mass in honor of the kidnapped schoolgirls in Abuja on May 11. Hide Caption 5 of 19 Photos: Photos: Nigerians protest over kidnapped girls Nigerians protest over kidnapped schoolgirls – Catholics nuns pray in Abuja on May 11. Hide Caption 6 of 19 Photos: Photos: Nigerians protest over kidnapped girls Nigerians protest over kidnapped schoolgirls – A woman attends a demonstration Tuesday, May 6, that called for the Nigerian government to rescue the girls. Hide Caption 7 of 19 Photos: Photos: Nigerians protest over kidnapped girls Nigerians protest over kidnapped schoolgirls – Community leader Hosea Sambido speaks during a May 6 rally in Abuja. Hide Caption 8 of 19 Photos: Photos: Nigerians protest over kidnapped girls Nigerians protest over kidnapped schoolgirls – Brig. Gen. Chris Olukolade, Nigeria's top military spokesman, speaks to people at a demonstration May 6 in Abuja. Hide Caption 9 of 19 Photos: Photos: Nigerians protest over kidnapped girls Nigerians protest over kidnapped schoolgirls – Women march Monday, May 5, in Chibok, Nigeria. Hide Caption 10 of 19 Photos: Photos: Nigerians protest over kidnapped girls Nigerians protest over kidnapped schoolgirls – People rally in Lagos on Thursday, May 1. Hide Caption 11 of 19 Photos: Photos: Nigerians protest over kidnapped girls Nigerians protest over kidnapped schoolgirls – Police stand guard during a demonstration in Lagos on May 1. Hide Caption 12 of 19 Photos: Photos: Nigerians protest over kidnapped girls Nigerians protest over kidnapped schoolgirls – Protesters take part in a "million-woman march" Wednesday, April 30, in Abuja. Hide Caption 13 of 19 Photos: Photos: Nigerians protest over kidnapped girls Nigerians protest over kidnapped schoolgirls – Obiageli Ezekwesili, former Nigerian education minister and vice president of the World Bank's Africa division, leads a march of women in Abuja on April 30. Hide Caption 14 of 19 Photos: Photos: Nigerians protest over kidnapped girls Nigerians protest over kidnapped schoolgirls – A woman cries out during a demonstration in Abuja on Tuesday, April 29, along with other mothers whose daughters have been kidnapped. Hide Caption 15 of 19 Photos: Photos: Nigerians protest over kidnapped girls Nigerians protest over kidnapped schoolgirls – A man weeps as he joins parents of the kidnapped girls during a meeting with the Borno state governor in Chibok on Tuesday, April 22. Hide Caption 16 of 19 Photos: Photos: Nigerians protest over kidnapped girls Nigerians protest over kidnapped schoolgirls – Mothers weep April 22 during a meeting with the Borno state governor in Chibok. Hide Caption 17 of 19 Photos: Photos: Nigerians protest over kidnapped girls Nigerians protest over kidnapped schoolgirls – Four female students who were abducted by gunmen and reunited with their families walk in Chibok on Monday, April 21. Hide Caption 18 of 19 Photos: Photos: Nigerians protest over kidnapped girls Nigerians protest over kidnapped schoolgirls – Borno state Gov. Kashim Shettima, center, visits the girls' school in Chibok on April 21. Hide Caption 19 of 19 
 
 JUST WATCHED US offering help for kidnapped girls Replay More Videos ... MUST WATCH US offering help for kidnapped girls 01:44 
 
 Britain is sending a small team of experts to complement the U.S. team, a spokesman for Prime Minister David Cameron said Wednesday. The spokesman didn't specify the nature of the team's expertise. 
 
 On behalf of China, Premier Li Keqiang offered satellite and intelligence services to aid in the search. 
 
 Meanwhile, Nigerian authorities offered a reward of about $310,000 on Wednesday for information leading to the rescue of the girls. 
 
 "While calling on the general public to be part of the solution to the present security challenge, the Police High Command also reassures all citizens that any information given would be treated anonymously and with utmost confidentiality," the Nigeria Police Force said in a statement. 
 
 According to accounts, armed members of Boko Haram overpowered security guards at an all-girls school in Chibok, yanked the girls out of bed and forced them into trucks. The convoy of trucks then disappeared into the dense forest bordering Cameroon. 
 
 The reward offer comes amid international outcry over the mass kidnapping in mid-April. The #BringBackOurGirls campaign initially began on Twitter. It quickly spread, with demonstrators taking to the streets over the weekend in major cities around the world to demand action. 
 
 Defending the response 
 
 Nigeria's President has been under enormous international pressure to step up efforts to rescue the girls after come after waiting three weeks to publicly acknowledge the kidnappings. 
 
 His administration, however, is defending its response -- even as details emerged this about a second mass kidnapping. At least eight girls between the ages of 12 and 15 were snatched Sunday night from the village of Warabe by Boko Haram, villagers said. 
 
 "The President and the government (are) not taking this as easy as people all over the world think," presidential spokesman Doyin Okupe said, adding that helicopters and airplanes have searched for the girls in 250 locations. More troops, he said, are on the way. 
 
 Despite the flurry of activity, the father of two of the schoolgirls taken by Boko Haram scoffed at the Nigerian government's response. 
 
 "We have never seen any military man there," said the father, who is not being identified for fear of reprisals by the government or Boko Haram. 
 
 "Had it been military men who went into the bush to rescue our daughters, we would have seen them." 
 
 Members of the U.S. Congress called for action, former U.N. Secretary-General Kofi Annan called the abductions "abominable" and Malala Yousafzai, the Pakistani children's rights activist shot in the head by the Taliban, spoke out, too. 
 
 "The girls in Nigeria are my sisters and it is my responsibility that I speak up for my sisters," Yousafzai told CNN's "Amanpour." 
 
 The U.S. first lady, Michelle Obama, was among the latest high-profile figures to take to Twitter about the girls' plight, tweeting a photo of herself holding a sign that read: #BringBackOurGirls. 
 
 "Our prayers are with the missing Nigerian girls and their families," she said in the post. 
 
 'I abducted your girls' 
 
 Boko Haram translates to "Western education is sin" in the local Hausa language, and the group has said its aim is to impose a stricter enforcement of Sharia law across Africa's most populous nation, which is split between a majority Muslim north and a mostly Christian south. 
 
 The United States has branded Boko Haram a terror organization and has put a $7 million bounty on the group's elusive leader, Abubakar Shekau. 
 
 A man claiming to be Shekau appeared in a video announcing he would sell his victims. The video was first obtained Monday by Agence-France Presse. 
 
 "I abducted your girls. I will sell them in the market, by Allah," he said. "There is a market for selling humans. Allah says I should sell. He commands me to sell. I will sell women. I sell women." ||||| The ruthless Islamic terrorist behind the kidnapping of hundreds of Nigerian schoolgirls is believed to be holed up in abandoned military bunkers deep inside a remote forest eight times larger than Yellowstone and teeming with "wicked and poisonous" snakes. 
 
 The dreaded Sambisa Forest, a game reserve in the northeastern part of the embattled nation, provides bloodthirsty Boko Haram leader Abubakar Shekau safe haven from Nigeria's security forces, many of whom are said to be afraid to venture into the wooded no man's land. The shadowy leader, his army of jihadist fighters and 276 teenage girls he vowed to sell into slavery or as child brides are believed to have melted into rugged wilderness. The girls are to be sold for as little as $12, according to reports. 
 
 The Nigerian government has reached out to the United States for help in hunting down the terrorists and has offered a $300,000 reward for information leading to Shekau's capture. But catching the continent's most-wanted man will require venturing into the 23,000-square-mile Sambisa, whose dangers have taken on mythical proportions. With confidence in Nigerian authorities completely eroded, local residents have reportedly pooled money for motorcycles to head into the forest in search of the girls missing since last month’s abduction, as well those who have been abducted since. At least two of the girls have died of snakebites, and roughly 20 others are believed to be ill, according to an intermediary. 
 
 Shekau made his evil plans clear in a video released Monday, in which he gloated about the kidnappings. 
 
 "I abducted your girls," Shekau said, in an hour-long video that opens with fighters shooting guns into the air and shouting "Allahu akbar!" "By Allah, I will sell them in the marketplace.” 
 
 Shekau's army is estimated to number from a few hundred to a few thousand fighters. The U.S. has offered to send a team to Nigeria to help the search efforts. A senior federal law enforcement source told Fox News that although the FBI has a permanent presence in Lagos, Nigeria, it’s "still unclear, what, if any” supplemental resources are being provided by the FBI. The FBI's elite Hostage Rescue Team is not in play at this time, the source said. 
 
 The forest's thorny vegetation is 6 feet high in some places, impenetrable without the use of heavy cutlasses to chop trails. According to locals, the wilderness was a primary grazing grounds for stray elephants from central Africa as a game reserve before 2006. It’s now believed that Boko Haram could be hiding in bunkers here previously used by the military to protect the indigenous residents of the region. 
 
 In recent days, Boko Haram has raided villages in and around the forest, including a raid Monday night on a village near the border with Chad, in which eight more girls were kidnapped. 
 
 Umar Maryah, a professor at Nigeria’s University of Maiduguri, told The Guardian that the forest hosts a large population of wildlife, including giant crustaceans, monkeys, antelopes, lions, elephants and ostriches. 
 
 Boko Haram militants are reportedly well-versed on the enormous forest and would likely see any military approach long in advance. 
 
 “It actually took the intelligence services a long time to discover that the game reserve had become a hideout for the sect,” one source told The Nation. “They waited three years until several lives had been lost before acting reluctantly on the intelligence advises … As a matter of fact, Sambisa is not the only hideout of the insurgents.” 
 
 The young hostages will be tactically transported from one base to another, typically during the cover of nightfall, to avoid detection, the source added. 
 
 Meanwhile, little is known about the group’s notoriously vicious leader. Shekau -- who is believed to be as young as 36 or as old as 45 -- was reportedly Boko Haram’s deputy leader until its founder, Mohammed Yusuf, was killed in a massive crackdown by local authorities in 2009. Shekau was initially thought to have also been killed during those attacks, but he later surfaced in a video claiming to be the terror group’s new director. 
 
 The U.S. Department of State is offering a reward of up to $7 million for information leading to Shekau’s location. In 2012, he was declared as a “specially designated global terrorist” for numerous bombings, including the August 2011 attack on the UN office complex in Nigeria’s capital, Abuja, that killed 23 people and injured dozens more. 
 
 Shekau, according to a BBC profile, is known as a “fearless loner” with a photographic memory, a complex and often paradoxical man whom is part intellectual, part terrorist. His nickname — Darul Tawheed — translates as a specialist in Tawheed, or the concept of monotheism in Islam. 
 
 “He hardly talks,” one journalist, Ahmed Salkida, told BBC. “He is fearless … He is one of those who believes that you can sacrifice anything for your belief.” 
 
 Shekau does not speak English, but is fluent in his native Kanuri, Hausa and Arabic languages. He reportedly does not even communicate directly with the group’s soldiers. 
 
 “A lot of those calling themselves leaders in the group do not even have contact with him,” Salkida told BBC. 
 
 Shekau, according to those who study the group, is known for being particularly brutal. 
 
 “I enjoy killing anyone that God commands me to kill — the way I enjoy killing chickens and rams,” he said in a clip released in 2012 after an attack in Kano, Nigeria, that killed more than 180 people. 
 
 In addition to being the group’s militant leader, Shekau also serves as its spiritual leader, Salkida said. 
 
 “He has a photographic memory and is well versed in theology,” he told BBC. 
 
 Meanwhile, on Wednesday, as many as 300 people were killed when extremists attacked the town of Gamboru Ngala on Nigeria's border with Cameroon, according to local reports. The attack and hundreds of casualties were confirmed Wednesday by Borno state information commissioner Mohammed Bulama who spoke to The Associated Press by telephone Wednesday. Shops and homes were set ablaze and razed in the attack, he said. 
 
 Nigerian federal Senator Ahmed Zannah said the attack lasted about 12 hours, according to the newspaper. The insurgents set homes on fire and gunned down residents who tried to escape from the flames. Zannah blamed fighters of Nigeria's homegrown Boko Haram terrorist network that has claimed responsibility for the kidnapping of 276 teenage girls and is threatening to sell them into slavery. 
 
 Boko Haram's five-year-old Islamic uprising has claimed the lives of thousands of Muslims and Christians. More than 1,500 people have died in their attacks so far this year. The insurgents say Western influences are corrupting and they want to impose an Islamic state in Nigeria, a country of 170 million where half the population is Christian, The Associated Press reports.
– Nigeria is apparently feeling the international pressure over its kidnapped girls, with the national police offering a $300,000 reward today for information that leads to their rescue, reports the BBC. (The move comes a day after President Obama promised that a US team would help the cause.) But Boko Haram, the group that kidnapped the girls and vows to sell them, remains as defiant and brutal as ever. A new attack in the town of Gamboru Ngala, near the border with Cameroon, massacred at least 150 villagers, reports CNN. Local media reports say militants opened fire on a crowd of people in a busy marketplace, set homes on fire, and shot residents trying to flee the flames over a span of 12 hours, reports the AP. A Nigerian senator says the death toll is "high—hundreds—but we are still awaiting details from the military authorities." (Click to read about one girl's description of how she escaped Boko Haram.)