CHADRON, Neb. (AP) — Authorities say they’re investigating the assault of a jail guard in western Nebraska who was on duty alone.

Dawes County Sheriff Karl Dailey says the incident happened Friday night at the county jail in Chadron.

An inmate in a cell block with four people assaulted the guard, who was working a shift alone.

Dailey says the guard did not have serious physical injuries and was able to call for assistance. Local police responded shortly. The inmate went back into the cell without further incident.

Dailey says there are usually two guards on duty at all times. He says he will have additional information soon.