People gather at a damaged building following an attack by Boko Haram in Maiduguri, Nigeria Monday, Dec. 28, 2015. Boko Haram Islamic extremists struck the northeastern Nigerian city of Maiduguri for the first time in months Monday with rocket-propelled grenades and multiple suicide bombers, witnesses said. At least 50 people were killed and the death toll could go higher. (AP Photo/Jossy Ola)