MARENISCO TOWNSHIP, Mich. (AP) _ Part of a state prison was locked down Monday after an inmate protest turned violent, injuring 14 corrections officers in Michigan's Upper Peninsula, officials said.

The incident started when 35 prisoners at in a medium-security section of the Ojibway Correctional Facility refused to leave a day room Sunday night.

About 15 of the inmates attacked officers, said Russ Marlan, spokesman for the Michigan Department of Corrections. The clash was quickly broken up, and the prisoners fled to their cells, Marlan said.

None of the officers' injuries was considered serious, though one was admitted to Grand View Hospital in Ironwood with chest pains. The others were treated and released, Marlan said. No inmates were reported injured.

The inmates involved were transferred to maximum security facilities and could face criminal charges, Marlan said.