At least four people have been killed in the northern Nigerian city of Gombe in a gun and bomb attack on a prison and police station, officials say.
Police say they repulsed the attack which they blamed on the radical Islamist sect Boko Haram.
The groups has carried out deadly attacks and assassinations across northern Nigeria in recent months.
Earlier on Friday, gunmen killed five people at a mosque in Kano, the main city in northern Nigeria, police said.
A police spokesman said the attackers arrived on motorcycles and opened fire at worshippers.
Nigeria is experiencing a surge in ethnic and sectarian violence.
Gombe has previously been targeted by Boko Haram. In January, an attack on a church in the city left six worshippers dead.
In the latest attack, police said they successfully defended a federal prison and police station following multiple explosions and a two-hour gun battle.
Officials said four civilians were killed and police and army officers were injured.