Bomb explosions, targeting police and government offices, have rocked the northern Nigerian city of Kano and witnesses say at least seven people have been killed. The number of injuries is not known.

The initial reports out of Nigeria's second-largest city say two separate police headquarters buildings and an immigration office were hit by the blasts late Friday. Kano's emergency coordinator, Abubakar Jibril, told VOA by phone that conditions in the city were chaotic. Jibril said officials with his agency could not reach the scene of the first blast because security forces stopped them.

Witnesses contacted by other reporters spoke of people fleeing the scenes in panic, while there were unconfirmed reports of gunfire erupting.

There was no immediate claim of responsibility, but the northern part of the country has seen a wave of bombings blamed on the shadowy Islamist extremist group, Boko Haram.

Nigeria, which is divided between a largely Christian south and a mostly Muslim north, has seen escalating sectarian violence in recent months. President Jonathan has declared a state of emergency in many parts of the north in response to the unrest, but the attacks have continued.

Boko Haram, whose name means “Western education is forbidden” in Hausa, the main language of the north, says it is working to implement Islamic law across Nigeria, Africa's most populous country.