Scores of people have reportedly been killed after suspected Boko Haram fighters, who arrived on motorcycles throwing bombs, raided a town in Nigeria's northeast Borno state.

The Reuters news agency, quoting residents, reported that scores had been killed in the town of Shani after nightfall on Saturday, but a police source said they had been unable to verify the death toll as communication to the town had been largely cut off.

"They rode on motorcycles and were more than 30 men. They started throwing bombs into houses ... then the Boko Haram fired shots at people fleeing," resident Ishaya Brimah told Reuters by phone from a nearby village on Sunday.

"They set ablaze the police station, houses and a telecom mast... I saw people fleeing, some bodies on the ground."

Shani is located in Nigeria's Borno state, the heartland of Boko Haram's five-year insurgency, which has displaced more than one million people.

The armed group is fighting to revive an Islamic caliphate in Nigeria's north. It is suspected to be behind Friday's attack on the central mosque in the second city of Kano, where at least 100 people died.