A screen grab made on January 20, 2015 from a video of Nigerian Islamist extremist group Boko Haram obtained by AFP shows the leader of the Islamist extremist group Boko Haram Abubakar Shekau delivering a message. Boko Haram has claimed a massive attack feared to be the worst in its six-year insurgency and threatened Nigeria's neighbours, as talks began for a regional response to the militants and fears grew of further violence. "We killed the people of Baga. We indeed killed them, as our Lord instructed us in His Book," Shekau said in the 35-minute message, which was posted on YouTube. AFP PHOTO / BOKO HARAM -- RESTRICTED TO EDITORIAL USE - MANDATORY CREDIT "AFP PHOTO / BOKO HARAM" - NO MARKETING NO ADVERTISING CAMPAIGNS - DISTRIBUTED AS A SERVICE TO CLIENTS -- / AFP PHOTO / BOKO HARAM / -