KANO, Nigeria (AFP) - Suspected Boko Haram Islamists in two attacks in northern Nigeria on Friday killed five Muslim worshippers in a mosque and attacked a prison and police station, officials said.
Police said gunmen shot dead five people shortly after evening prayers inside a mosque in Kano, Nigeria's second largest city and the scene of deadly attacks that killed 185 people last month.
Kano state police spokesman Magaji Majia told AFP that two gunmen "opened fire on a congregation in a mosque around 6:30 pm (1730 GMT) and killed five people." He refused to speculate on who was behind the attack.
There were around 30 worshippers inside the mosque at the time.
"It is clear the attack was carried out by Boko Haram, and Sule Kwaram (the vigilante head) was the primary target," said a witness, Baffa Hayatu.
Hours later, an AFP reporter heard five explosions in the city, around the same area where security forces had exchanged fire with gunmen during an attack on a checkpoint on Wednesday. Kano is under a nighttime curfew.
Elsewhere in Nigeria's increasingly volatile north, gunmen also suspected to be from the Islamist militant group launched simultaneous gun and bomb attacks on a prison and a police station in downtown Gombe city.
A jail guard and a resident said the attackers were battling to gain entry to the prison in an apparent bid to free its members suspected held there. The sect has previously targeted Christian worshippers in Gombe.
"We are under siege. A large number of gunmen have encircled the prison, shooting and detonating explosives. It is clear they are Boko Haram," a warden told AFP from inside the prison before his phone went dead.
A resident, Ibrahim Yau, said gunshots and explosions rang across the city for over an hour.
"There has been shooting and bomb attacks at the district police station in the centre of the city, and also the central prison," he said.
The prison overlooks the police station and both are situated near the palace of the traditional Muslim leader, the emir, in downtown Gombe, the capital of a state that goes by the same name.
Authorities immediately imposed a 24 hour curfew on the city.
Boko Haram launched an uprising in 2009 put down by a brutal military assault that left some 800 people dead.
After lying dormant for about a year, it has re-emerged with a series of shootings and bomb attacks that rights groups say have killed more than 935 people.
The sect's deadliest ever assault left 185 people dead last month in Kano.
The group claimed responsibility for the Christmas Day bomb attack on a Roman Catholic Church outside Abuja which claimed at least 44 lives.
A previous bomb attack last August on the UN headquarters building also claimed by the sect killed 25 people.
Witnesses and a medic said an attack this week on a market blamed on the sect in Maiduguri, Boko Haram's home base, left 30 vendors dead.
Nigerian military authorities this week said they had been able to link activities of Boko Haram to Al-Qaeda in the Islamic Maghreb.