The incident happened at the shooting range at London Police Service Headquarters.
The officer was taken to hospital and is listed in stable condition.
London police and the RCMP are investigating. Neither agency released further details.
London police spokesperson Melissa Duncan said the RCMP is one of a few outside agencies that use the gun range for training purposes.
Duncan directed all other questions in regard to the shooting to the RCMP.
RCMP spokesperson Richard Rowlings was not available for comment.