Updated

Survivors say soldiers fled and left five villages and a town at the mercy of Islamic extremists who killed 13 people and bombed a theological school in attacks in northeast Nigeria.

The latest violence in an Islamic uprising comes amid widespread criticism of military failures including from Senate president David Mark who questioned how "this mayhem persists ... under emergency rule when security operatives are on red alert."

A pastor said outnumbered and outgunned soldiers abandoned checkpoints and fled into the bush when extremist fighters attacked villages and a town in Adamawa state for several hours Wednesday night.

At least 59 students were killed in a school attack in neighboring Yobe state Tuesday.

Nigeria began official centenary celebrations Thursday of the unification of the mainly Muslim north and Christian south.