LINCOLN, Neb. (AP) — Nebraska prison officials say they’re investigating two more assaults on staff members this week, adding to a string of physical violence against employees over the past two months.

Two staff members at Tecumseh State Correctional Institute were attacked by inmates Friday following a religious service. Both were taken to an outside medical facility for treatment.

Three staff members at the Nebraska State Penitentiary in Lincoln were assaulted Thursday while trying to break up a fight between inmates. All three were hospitalized for non-life-threatening injuries and released.

Corrections department spokesman Andrew Nystrom says the units where the assaults took place are on lockdown and investigations into the incidents are under way.