LINCOLN - State prison system officials say an inmate has assaulted two staffers at the Nebraska State Penitentiary in Lincoln.

A Nebraska Department of Correctional Services news release says the assaulted happened Tuesday morning in the prison's yard, when multiple groups of men started fighting, and staff had to intervene.

The release says one inmate managed to slip out of his restraints as the group was being escorted back inside and repeatedly punched a nearby staffer and attacked another staffer who came to help.

Both staffers were treated at a local hospital for injuries described as serious.

The release says the Lancaster County Attorney will determine whether to bring charges in the attack once the investigation is complete.