Suspected Islamist militants have attacked churches in several towns in northeastern Nigeria, leaving at least 24 people dead.

Witnesses and local officials say the gunmen on motorcycles hit the villages Sunday near Chibok in Borno state. Witnesses accused the Nigerian military of being slow to respond to the attack.

There has been no immediate claim of responsibility for the attack.

In April, rebels from the militant group Boko Haram kidnapped more than 270 girls from a school in Chibok. Officials say 219 of them remain unaccounted for.

The violence Sunday is the latest in a regular series of attacks in northeastern Nigeria that has continued despite the government declaring a state of emergency and sending extra troops to the region.  

Boko Haram militants have killed thousands of people during their five-year insurgency to establish an Islamic state in Nigeria's northeast, with attacks on schools, churches, mosques, bus stations and other public places.