An unknown number of inmates at the Atlantic Institution in Renous were taken to hospital last Friday after being assaulted within the maximum security prison.

RCMP and prison staff are investigating the assaults, which took place Dec. 1 at about 6:20 p.m., according to a news release Wednesday from the Correctional Service of Canada.

The prison has been under lockdown since then as staff conduct an "exceptional search" of part of the institution, the release says.

No staff members were injured in the incident.

Few other details were released, including how many inmates were assaulted, and how.

CBC News has asked the Atlantic Institution for more information.