Inmates at a Gravenhurst prison were placed in lockdown after an alleged assault on Thursday.
Provincial police were called to Beaver Creek Institution for reports of an assault with a weapon.
Police say a 30-year-old man was taken to the hospital with undisclosed injuries, treated and has since been returned to custody.
Correctional Services Canada (CSC) reports staff conducted an extensive search of the prison.
No other injures were reported.
"The safety and security of institutions, their staff, and the public remains the highest priority in the operations of the federal correctional system," CSC stated in a report regarding the alleged assault.
CSC said there would be a review of the circumstances surrounding the incident to “improve practices aimed at preventing this type of incident.”
OPP continues to investigate.
