Three inmates at the federal prison in Renous were stabbed and taken to hospital last week, RCMP confirmed Thursday morning.
The stabbing at the maximum security prison, between Blackville and Miramichi, involved several inmates.
Cpl. Jullie Rogers-Marsh, a spokesperson for the RCMP in New Brunswick, said two inmates who were stabbed were treated in hospital and returned to the prison.
A third inmate was more severely injured and had to stay in hospital. Rogers-Marsh wasn't sure if he was still there or back at the prison.
"The third individual that was kept had serious but non-life-threatening injuries," she said.
The assaults at the Atlantic Institution happened on Friday just before 6:30 p.m., according to a news release from the Correctional Service of Canada.
Rogers Marsh said RCMP in Blackville were called to the scene just after 7:30 p.m.
The prison was put under lockdown as staff conducted an "exceptional search" of part of the institution, the release said.
No staff members were injured in the incident.
Few other details were released, but the released said the prison is still under lockdown.
The Correctional Service of Canada is investigating the circumstances and continues to work with the police.
CBC News has tried for more information from the prison and is still waiting for an update.