At least 20 people, mostly students, have been killed by unknown gunmen in Mubi, north-eastern Nigeria, BBC News reported citing a police source.

The attack happened at a student hostel away from the Federal Polytechnic Mubi campus, the source said.

One Mubi resident told the BBC that more than 40 students had been killed but there is no official death toll.

The reported killing comes days after a major operation against the Boko Haram militant group in the town.

National Emergency Management Agency spokesman Yushua Shuaib confirmed the attack to the Reuters news agency but had no details on casualties.

He said it was not clear whether the attack was the work of Boko Haram, or the result of a dispute between rival political groups at the university.

A Red Cross official said at least 10 people had died, reports the AFP news agency.

BBC Nigeria correspondent Will Ross says mobile phone masts in the area were recently attacked by the militants, so getting information from Mubi is difficult.