A 24-hour curfew is in effect for the northern Nigerian city of Kano as an Islamist extremist group claimed responsibility for a coordinated series of bombings that targeted police and government offices.

Panic ensued with people fleeing on foot and by car after the bombs exploded and gunfire rang out Friday. The trouble started after 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. Scores of people are believed dead, including the suicide bomber and other attackers who died following 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.

The Islamist extremist group, Boko Haram, has claimed responsibility. A group spokesman called journalists to say 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.

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.