Updated

A Nebraska prison has been placed on lockdown and inmates are refusing to return to their cells.

Officials say approximately 40 inmates are involved in the disturbance Thursday at the Tecumseh State Correctional Institution.

No injuries have been reported. The department says in a statement that all staff members are safe and accounted for, and an emergency response team is now active. The statement says the incident is isolated to half of a housing unit and poses no risk to the public.

The prison in southeast Nebraska was the site of a May 2015 riot that injured several staff members, caused widespread damage and left two inmates dead.