Boko Haram Pledges Allegiance to ISIS Extremist group tweets allegiance to 'Caliph of the Muslims' By Newser Editors and Wire Services Posted Mar 7, 2015 4:10 PM CST 32 comments Comments People gather at the site of a bomb explosion at a market in Maiduguri, Nigeria, Saturday, March 7, 2015. (Jossy Ola) (Newser) – Nigeria's home-grown Boko Haram Islamic extremists have pledged formal allegiance to the Islamic State group, in a message allegedly by a Nigerian insurgent leader posted on Twitter and reported by the SITE Intelligence monitoring service. The unverified pledge posted today comes as the Nigerian militants reportedly are massing in a northeastern town for a showdown with a multinational force that has dislodged them from a score of towns in recent weeks. Boko Haram leader Abubakar Shekau made the oath in Arabic in a tweet saying: "We announce our allegiance to the Caliph of the Muslims." Islamic State leader Abu Bakr al-Baghdadi has declared himself the caliph. Police say four suicide bomb attacks hit the city of Maiduguri today, killing at least 54 people and wounding 143 in the heartland of Nigeria's northeastern Islamic extremist uprising.