LINCOLN, Neb. — Officials say a prisoner assaulted three staff members at the Nebraska State Penitentiary in Lincoln.

The attack took place around 2:15 a.m. on Tuesday. The Department of Correctional Services says the staff members were responding to a medical emergency after seeing the inmate agitated and blood in his cell.

Officials say the inmate struck three staff members in the head and shoved one of their heads into a wall before he was subdued.

All three staff members were taken to a hospital for evaluation. One did not suffer a treatable injury, one suffered a sprain and one suffered a possible concussion.

The department is investigating the incident.