LINCOLN, Neb. (AP) — A Nebraska State Penitentiary correctional officer has undergone surgery for broken bones in his face after being attacked by an inmate.

The attack occurred Monday at the Lincoln prison. Nebraska Department of Correctional Services Director Scott Frakes confirmed the attack Friday to the newspaper.

Frakes says the officer had ordered the inmate to stand for a search. Frakes say the inmate refused to comply, then hit the officer, knocking him to the ground and hitting the guard several more times.

Other officers restrained the inmate and took the assaulted guard to a hospital.

A prison spokesman says the attack is under investigation and results will be forwarded to the Lancaster County Attorney’s Office.