Nigerian police say at least seven people have been killed in a coordinated series of bombings that targeted police and government offices in the northern city of Kano.

The predominantly Muslim city is under a 24-hour curfew following Friday's attack claimed by the radical islamist group Boko Haram.

The French Press Agency said there also explosions in the Southern city of Yenagoa following the blasts in Kano, but no one was injured.

In Kano a suicide bomber set off one large explosion at the office of the city's Inspector General of Police. A few minutes later, explosions could be heard at other locations in Nigeria's second-largest city. The suicide bomber died in the blast while other attackers perished in gun battles with police.

A reporter for VOA's Hausa Service says that over a period of 90 minutes, he counted more than 24 blasts. Kano's emergency coordinator, Abubakar Jibril, also described conditions in the city as chaotic. Jibril told VOA that officials with his agency could not reach the scene of the first blast because security forces stopped them.

A spokesman for Boko Haram told reporters the bombings were in retaliation for the arrest of several Boko Haram members in Kano.

Nigeria, which is divided between a largely Christian south and a mostly Muslim north, has seen escalating sectarian violence in recent months.

President Goodluck Jonathan has declared a state of emergency in many parts of the north in response to the unrest, but the attacks have continued. Kano had been relatively free of violence and was not included in the emergency area.

Last month, Boko Haram claimed responsibility for four bombings on Christmas that killed 39 people, including dozens at a Catholic Church near Abuja.

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