Boko Haram   militants have disguised themselves as preachers in order to carry out a savage gun massacre in northern Nigeria that left at least 24 people dead. The Islamic extremists drove cars to a mosque in the remote village of Kwajafa in Borno state, where they told locals they were there to teach Islam. Once a crowd had gathered around the men, the jihadis opened fire  using handguns and assault rifles before setting fire to nearby houses that were filled with unsuspecting families. The attack came as new pictures showed how teenagers caught up in previous slaughters carried out by Boko Haram in neighbouring Chad are being encouraged draw spine-chilling pictures of the attacks as part of their therapy. Memories: The attack came as new pictures showed how teenagers caught up in previous slaughters carried out by Boko Haram are being encouraged draw pictures of the attacks as part of their therapy . Heartbreaking: The chilling images illustrate the innocence of the young victims murdered by the jihadis . Shocking: Young men and women at a refugee camp near Baga Sola in Chad were photographed drawing bloody scenes of assault rifle-wielding gunmen carrying out slaughters from the back of pick-up trucks . Boko Haram's six-year insurgency in Nigeria, and President Goodluck . Jonathan's failure to end it were key factors . in the victory of opposition candidate Muhammadu Buhari in last . week's election. The group fighting for an Islamic state has killed thousands . and kidnapped hundreds, although a military operation against . them by Nigeria and neighbours Chad, Cameroon and Niger in the . past two months has wrested back much of the territory it . controlled. 'People didn't know the Boko Haram men came for attack . because they lied to our people that they came for preaching,' said Buba in a telephone conversation. 'They opened fire on them and killed many people,' he said, . adding that houses were set on fire. Some people were being treated for gunshot wounds and burns . at a hospital in the Borno state town of Biu on Monday, a source . there said. Young Nigerian refugees draw  during a therapy program managed by UNICEF in Baga Sola refugee camp . Young Nigerians refugees play on April 6, 2015 in a refugee camp near Baga Sola. Seven civilians were killed in an attack in Chad blamed on Nigerian Boko Haram rebels, officials said on April 6.     AFP PHOTO / PHILIPPE DESMAZESPHILIPPE DESMAZES/AFP/Getty Images . Last week the U.N.'s human rights chief said Boko Haram fighters have been murdering dozens of young women and girls they had taken as 'wives' and using children as 'expendable cannon fodder'. As the Islamist militant group has retreated from parts of northeastern Nigeria, 'gruesome scenes of mass graves and further evident signs of slaughter,' has been brought to light, Zeid Raad al-Hussein told a special session of the U.N. Human Rights Council in Geneva. Boko Haram's reported use of children as shields and human bombs would, if confirmed, constitute war crimes and crimes against humanity, he said. This comes in response to recent reports that hundreds of women and children had been seized from Nigerian primary schools by Boko Haram militants to be used as 'human shields'. The Islamists took as many as 500 adults and children from primary schools in the north-eastern town of Damasak in late February, Mike Omeri, spokesman for the fight against Boko Haram, said. Still there: A boy is photographed yesterday walking past a burnt house and car in N'Gouboua, near Lake Chad in Chad, which was attacked by Islamist group Boko Haram earlier in the year . Today it emerged that those caught up in deadly attacks by Boko Haram - who declared their allegiance to the Islamic State terror group earlier this year - have been asked to draw pictures of the massacres as part of their therapy. Young men and women at a UNICEF-run refugee camp near Baga Sola in Chad were photographed using pencils and crayons to draw bloody scenes of assault rifle-wielding gunmen carrying out slaughters from the back of pick-up trucks. The chilling creations illustrate the innocence of the young victim savagely murdered by the jihadis. Boko Haram has been waging a guerilla war in northern Nigeria and also attacked towns in neighboring countries, prompting nations in the region including Chad and Niger to put together a force to combat them. The newly elected president of Nigeria, General Muhammadu Buhari, who beat incumbent Goodluck Jonathan in a landslide win last night, has promised to 'stamp out' the insurgency . In Kano state, where Boko Haram's 'war' on the civilian population has been most prominent, Buhari delivered a crushing defeat to Jonathan, winning 1.9 million votes for Jonathan's 215,800. Sorry we are not currently accepting comments on this article.
Cold-blooded jihadis drove to a mosque in the remote village of Kwajafa .
Disguised killers told locals there were there to teach them about Islam .
Once a crowd had gathered, the militants opened fire with assault rifles .
They then set about setting fire to houses filled with unsuspecting families .