Witnesses say at least seven police officers have been killed in northeast Nigeria in separate attacks likely carried out by a radical Islamist sect operating in the region.
The attacks happened on Sunday in Borno state, where the sect known as Boko Haram once had its main mosque.
Witnesses said gunmen attacked the Maiduguri home of a former senator, killing one police officer, and also killed three others around the city.
Witnesses said gunmen killed two other police officers in the village of Mafa, about 40 kilometers (25 miles) away from Maiduguri.
Boko Haram is waging a bloody fight against Nigeria's weak central government in an effort to bring Shariah law to the multiethnic nation of more than 160 million people and free its imprisoned members.