yola nigeria suicide bomber kill least 50 people northeastern nigeria tuesday attack mosque bore hallmarks faction islamist militant group boko haram bomb mubi adamawa state one deadly nigeria northeast since president muhammadu buhari come power 2015 pledge end boko haram eight-year insurgency attack group civilian military target bring least 278 number people kill 2017 accord calculations reuters claim responsibility dead piece beyond recognition say bayi muhammad worshipper escape blast late early morning prayers abubakar othman police spokesman adamawa state say death toll least 50 add tally could rise eight people critically injure 30 others hurt stable condition say idris garga northeast regional coordinator nigeria national emergency agency boko haram hold territory adamawa state 2014. troop push early 2015 town mubi relatively peaceful tuesday bomb statement tuesday nigeria president say attack cruel give assurances government would everything require secure state boko haram militant group often mount suicide attack public place mosques market last december two schoolgirl suicide bombers kill 56 people wound dozens market adamawa mosque blast bear hallmarks faction lead abubakar shekau force women girls carry suicide bomb attack often leave bomber dead boko haram wag insurgency northeastern nigeria since 2009 attempt create islamic state region kill 20,000 force around million people flee home group split 2016 faction shekau base sambisa forest border cameroon chad mainly target civilians suicide bombers faction base lake chad region lead abu musab al-barnawi mainly attack military force quietly build strength past year attack focus borno state birthplace insurgency group hold land around size belgium borno adamawa yobe state early 2015 force nigeria army troop neighbor countries suicide bomber kill 50 nigeria mosque attack