The Special Investigations Unit issued a news release Tuesday regarding an incident that happened on Lakeshore Road East, just east of Hurontario Street.
An officer was dispatched to the location at approximately 1:15 p.m. on Tuesday.
Shots were fired and a 50-year-old man was wounded in the arm.
The man was taken to a Mississauga hospital.
The SIU investigates all incidents involving police in which death or serious injury have occurred, or in which allegations of sexual assault are raised.
Five investigators and three forensic investigators are now probing the incident in Mississauga.