The Nigerian army is fighting to retake a town captured by Boko Haram forces in northeastern Borno State.
World Watch Monitor reports that more than 100 people died when the radical Islamic group conquered Gwoza last week.
They killed at least one church leader and burned down churches, homes, businesses, and government buildings.
Boko Haram has intensified its campaign against churches in recent weeks.
On July 30, it destroyed at least five churches in a mostly Christian enclave of Borno.
A few days earlier, a female suicide bomber attacked St. Charles Catholic Church in Kano State.