Kenya defeats terrorists after four-day siege Kenyan president said task to defeat attackers at a shopping mall in Nairobi has been completed. Kenyan president said five terrorists have been killed and 11 suspects are in custody. Forensic investigations are underway to ascertain involvement of 2 or 3 Americans and 1 British. 24 (Xinhua) -- Kenyan president Uhuru Kenyatta said on Tuesday that the task to defeat attackers at a shopping mall in Nairobi has been completed after four days of fighting which saw a death toll of 72 people, including five terrorists. "We have ashamed and defeated our attackers," Kenyatta said in a televised address, noting "that part of task has been completed. " He said five terrorists have been killed and 11 suspects are in custody. A total of 67 people were killed by the gunmen who stormed the upscale shopping mall on Saturday, including 61 civilians and six security officers, according to the president. The number of casualty is set to rise as, according to the president, there are still bodies trapped inside the building including those of terrorists as part of the mall collapsed. Kenyatta declared three days of national mourning starting Wednesday. Somali militant group Al-Shabaab has claimed responsibility for attack, the bloodiest assault in Kenya since the U.S. Embassy was bombed in 1998. Kenyatta's remarks came as the fate of the civilians who may still be hiding in the mall or held by hostage by terrorists remained unclear as the Kenya Red Cross Society said some 60 people remain unaccounted for. A forensic team is still at the scene of the attack, Kenyatta said. He vowed to intensify operation against terrorism in the region. I promise that we shall have a full accountability for the mindless destruction, deaths, pain, loss and suffering we have all undergone as a national family. These cowards will meet justice, as will their accomplices and patrons, wherever they are," he said. The president lost a nephew in the bloodbath. A group of masked gunmen numbering between 10 and 15 stormed the upscale Westgate shopping mall around Saturday noon, shooting ruthlessly at shoppers and hurling grenades, causing 240 casualties. The militant group said later on its twitter feed that the attack was part of retaliation for Kenya's military intervention in Somalia in October 2011 and that it demanded Kenya withdraw troops from the country. However, the demand was rejected by Kenyatta who said on Sunday that Kenya would not relent in its resolve to fight global terrorism. The tense standoff between security forces and Al-Shabaab militants persisted for four days, featuring sporadic gunfight, explosions, fire and thick smoke billowing. Kenyatta said forensic investigations are underway to ascertain the involvement of two or three Americans and one British woman in the attack. Kenya's cabinet secretary for foreign affairs and international trade Amina Mohamed earlier told America's Public Broadcasting Service's NewsHour program that "two or three Americans and one Brit" were among the attackers who carried out the shooting spree. The Americans were 18 to 19 years old of Somali or Arab origin and lived "in Minnesota and one other place" in the U.S., she said. Canadian, British, Chinese, Ghanian, French, South African are among the victims of the carnage. The attack in Kenya has aroused wide condemnations from United Nations, African Union, Western powers, African peers and others that also sent condolences to the victims and offered support to combat terrorism. Following the attack, Kenya has beefed up security along borders between Kenya and Ethiopia and between Kenya and Somalia to prevent insurgents from neighboring countries from passing to launch incursion, according to Cabinet Secretary in charge of Internal Security Joseph Ole Lenku. Kenya has maintained its enviable reputation as an island of peace in a sea of turmoil since independence in 1963. However, the increased insurgency during recent years, particularly the Saturday attack on the mall with security guards at each entrance, pushes Kenya to review its counter-terrorism measures. At a televised emergency session of the National Assembly on Tuesday to discuss the security situation of the weekend tragedy, lawmakers vented their outrage at the security lapse in the country and pushed for reforms in the security system. Timothy Wanyonyi in whose constituency the terror attack happened lamented over huge intelligence gathering failure before the attack, according to local media Standard. Majority leader Adan Duale whose Garissa Township constituency has been engulfed in terror since Kenya sent troops into Somalia said the raid should be a wake-up call for the government to institute security reforms. Werunga Simiyu, a regional security expert who spoke to Xinhua on Monday emphasized that the current counter-terrorism measures in Kenya have not adequately tackled this challenge. As neighboring countries in the horn and central African region roiled in civil strife, Kenya remained peaceful and played host to millions of refugees fleeing bloodshed in Somalia, Ethiopia, Eritrea, Sudan, Democratic Republic of Congo, Rwanda and Uganda. Instability in the region has obviously bred terrorism that has crossed our borders. There is no denying militias and rebel groups found a safe haven in Kenya where they could plot and execute their destructive schemes," Simiyu said. He regretted that Kenya's vulnerability to terrorist activities has been worsened by lax security measures at border points while limited technology and resources undermine detection and early warning to foil major attacks. Our vigilance has not been adequate and should be strengthened through adoption of cutting edge technologies and retraining of an inter-agency unit charged with combating terrorism. Every loophole that allows terrorists to enter the country and set up base undetected should be sealed," Simiyu stressed. "It is appropriate at this juncture for Kenya to revamp her security architecture to combat terrorism effectively," he said. The multi-storey Westgate mall, consisting of more than 80 shops as well as a Nakumatt supermarket, used be a place for wealthy Kenyans, foreigners and tourists to shop and relax. Now, it reminds people of not only the bloody tragedy but also risks they might face when shopping in big malls and supermarkets. Kephas, from security guard company Securex who works at the construction site about 500 meters from the mall, was deeply saddened as his colleague who was on duty at the mall was killed by the gunmen. He said Kenyan citizens and tourists must be shocked by the attack with a carry-over of fear. People will become suspicious and too scared to go to shopping malls and supermarkets.  Because you will never know whether there are terrorists around you," he said. Kenya's leading supermarket Nakumatt was among the most affected by the attack with the Westgate and Ukay branches remaining shut down. Kenya Private Sector Alliance chief executive officer Carole Kariuki told Daily Nation newspaper that the business community has suffered a huge blow in the attack. Whereas it is too early to quantify losses, a lot is going on in there. From what is being destroyed to the general closure of the mall and other shopping outlets and the many employees that have lost their lives, it's going to be a big loss to this nation, " Ms Kariuki said. The attack would also deal a further blow to the east African nation where tourism is a pillar industry, which is already dented by increased insurgency after Kenya launched cross-border incursion into Somalia to pursue the militants. "We wish to assure tourists that Kenya is peaceful and our security agencies are doing everything possible to ensure that every one is safe," Kandie said, extending welcome to tourists to visit all tourist facilities across the country that are operating normally. News Analysis: Attack on Kenya's Westgate inside mind of terrorist 24 (Xinhua) -- The siege of the Westgate shopping mall in Nairobi by a group of Al-Shabaab militants played out before the eyes of stunned Kenyans like a movie. This is the deadliest act of terrorism since the 1998 U. S. Embassy bombings in Nairobi, which killed over 100 people, both Kenyans and Americans.