Kano, Nigeria - Suspected Boko Haram Islamists razed a police station and killed 14 people, whose charred bodies were found, in an overnight raid in Nigeria's northeastern city of Gombe, witnesses said Saturday.

The city was put under lockdown, with no residents allowed to leave their homes, after the gun and bomb assaults where attackers also tried to break into a prison in a botched attempt to free inmates, witnesses and local radio said.

Boko Haram, responsible for a wave of recent raids in northern and central Nigeria, have repeatedly claimed its members are being illegally held in state prisons and demanded their release.

Many of Boko Haram's recent attacks have targeted the police.

Suspected members of the group also gunned down five worshippers inside a mosque on Friday as evening prayers ended in Kano, Nigeria's second largest city.

Later in Kano explosions were heard. Residents said gunmen stole a car belonging to the country's electoral commission, but it appeared to have stalled a few hundred metres (yards) later, and they blew it up.

Boko Haram's violent campaign has intensified in recent months and on Thursday Nigeria's top military chief said the group had formed links with al-Qaeda's north Africa branch, known as Al-qaeda in the Islamic Maghreb.

“I have seen at least 14 burnt bodies in and around the police station,” a witness in Gombe said on condition of anonymity.

He said he counted 10 bodies inside the police building, adding the victims could be policemen, while four others were found dead in a burned out car outside the station.

“At a roundabout between the police station and the prison there was a car that was burned out with all its four occupants. It's not clear who they were,” he added.

Locals said the police station was burned to the ground in the attack.

Another resident, Babandi Ali, said “the police station has been razed and there are burnt bodies inside, but I couldn't confirm how many.” He confirmed the burnt out car at the roundabout with four bodies inside.

A jail guard told AFP late on Friday that prison officers battled Boko Haram gunmen who tried to gain entry to the prison in an apparently failed bid to free group members being held there.

“The prison is intact,” a resident who lives nearby said.

The prison overlooks the police station and both are situated near the palace of the emir, the top traditional Muslim leader in the city of Gombe, the capital of a state of the same name.

Boko Haram has previously targeted Christian worshippers in Gombe.

Authorities were not immediately available for comment, but local radio said officials had imposed a 24-hour curfew across the city.

Boko Haram launched an uprising in 2009 in Africa's most populous nation, which was put down by a brutal military assault that left some 800 people dead.

After lying dormant for about a year, the group has re-emerged with a series of shootings and bomb attacks that have killed around 1,000. Rights groups in January had a toll of more than 935 people. Dozens of others have been killed since then in attacks blamed on the sect.

The sect's deadliest assault left 185 people dead in Kano last month.

The group claimed responsibility for the Christmas Day bomb attack on a Catholic Church outside the capital Abuja that claimed at least 44 lives.

Witnesses and a medic said 30 vendors died in a attack on a market this week in Maiduguri, Boko Haram's home base. - Sapa-AFP