Beaver Creek Institution in Gravenhurst has been locked down due to a search for illegal contraband.
On Tuesday, staff initiated the lockdown procedure after suspecting contraband to be within the medium-security federal prison.
Correctional Service Canada spokesperson Kyle Lawlor says this means all regular day-to-day activities are shut down.
Lawlor says the lockdown will stay in place until officials at the facility are satisfied that safety has been restored.
There are no details on what the contraband is that guards are searching for.