RCMP say a man who was banging on the main entrance of the detachment in Fort Chipewyan in northern Alberta on Thursday night was shot and injured by an officer.
It was just before midnight and the building was closed.
An officer had responded to the disturbance and a second Mountie who was off duty saw what was going on and came to help.
Police say it was during an altercation that one of the officers fired a firearm.
The suspect sustained a non-life-threatening injury and was taken to hospital for treatment.
Neither officer was hurt.
The Alberta Serious Incident Response Team, which reviews serious actions involving police, is investigating.
The Canadian Press