Burnt out school block following a gun battle and explosions by the Boko Haram sect in Potiskum, Nigeria, Saturday, Oct. 20 , 2012. A Chinese construction worker has been killed in a besieged city in Nigeria’s northeast, an official said Friday, exacerbating security concerns for foreign workers in Nigeria’s violence-wracked northeast, while an overnight raid in a nearby city left 5 others dead and several schools razed to the ground. (AP/Photo Adamu Adamu) Photo: AP / AP