Police in the northern Nigerian city of Kano say at least 13 people were killed when a mob attacked a police station Tuesday.

Police say the assailants killed the officer in charge, his wife, and 11 other officers during the daylight attack.

The attackers are suspected to belong to a radical Islamic group.

It was not clear if the attack is related to Nigeria's elections. Nigerian newspapers say violence during state elections Saturday killed at least 50 people.

Police have declared a nationwide ban on political rallies in an effort to prevent further violence.

Some information for this report was provided by AP and Reuters.