Stony Mountain Institution has been placed under a lockdown after three inmates were assaulted.

The Correctional Service of Canada (CSC) said Thursday around 7:40 p.m. three inmates were assaulted in the medium security unit.

The injured inmates were evaluated by staff and transported to hospital for treatment. STARS was dispatched to the scene around 8:30 p.m. and transported one inmate to Health Sciences Centre in Winnipeg.

Assistant Warden JL Meyer said the inmates remain in hospital, and the nature of their injuries cannot be disclosed due to privacy reasons.

No staff or other inmates were injured, said CSC.

The warden ordered a lockdown and a general search of the medium and maximum security units. Meyer said the lockdown is expected to be in effect for at least a few days, and normal operations will resume when it’s considered safe to do so.

Visits have been suspended while the search is underway.

Stonewall RCMP along with Stony Mountain Institution and CSC are investigating the incident.