Witnesses say multiple explosions have rocked the northern Nigerian city of Kano.

A local journalist tells VOA that the blasts went off Friday afternoon and damaged at least one police station.

Other witnesses report hearing gunfire and seeing smoke rising from different parts of the city.

Nigeria is trying to cope with a wave of bombings and shootings in the north, most of it blamed on the radical Islamist sect Boko Haram. The shadowy group has claimed responsibility for several of the deadly attacks.

President Goodluck Jonathan has vowed to crush the group. Last month, he declared a state of emergency in 15 areas and deployed troops in an effort to maintain order.