Blasts and shootings shook residents of Potiskum, previously hit hard by violence blamed on Islamist extremist group Boko Haram, residents said.

The police commissioner for Yobe state, where Potiskum is located, said there had been a bomb explosion and security forces afterward cordoned off the area and began house-to-house searches.

He did not say whether there had been any casualties.

"There was a bomb explosion this morning and the Joint Task Force has already cordoned off the area for the safety of residents," Patrick Egbuniwe said, referring to a military and police task force.

"Right now, there is a house-to-house search by JTF to fish out the perpetrators of the terror attack."

Residents said the unrest began just before 6:00 am.

"It started with a huge explosion followed by successive blasts and gunfire," one resident told AFP.

The blasts and gunfire came from an area of the town where a bank, a military base and the office of the anti-narcotics agency are located, residents said.

Potiskum, the commercial hub of Yobe state, has been hard hit by Boko Haram attacks in recent months.

On Tuesday, Nigeria's military said 24 Boko Haram members were killed in violence that rocked the city of Maiduguri after the extremists launched attacks with bombs and rocket-propelled grenades.

The military has been regularly accused of abuses, including the killing of civilians. Tuesday's statement said there were no civilian casualties and one soldier was wounded, but the claims could not be independently verified.

Maiduguri is considered the base of Boko Haram. The conflict is believed to have killed at least 2,800 people since 2009.