STILLWATER, Minn. — State corrections officials are investigating an incident that left four workers injured at the Stillwater prison.  

Minnesota Department of Corrections spokesman John Schadl says one contract employee and a prison guard were taken to a local hospital Wednesday after an altercation and later released. Schadl says two additional employees suffered minor injuries and did not require hospital treatment.

Schadl declined to provide details about the incident at the men’s prison. The Star Tribune says it’s not clear what role inmates might have played in the altercation.