The Special Investigations Unit is looking into an incident that closed a busy intersection in St. Catharines.
The SIU says Niagara Regional Police officers were called to the area of Dunkirk and Bunting Roads Monday at noon, to respond to a man in distress.
Once on scene, officials say the man was located inside his vehicle.
The SIU says attempts were made to talk to the man, and at some point, two officers fired an Anti-Riot Weapon at the man.
The weapon is used to subdue without causing serious harm, and is classified a firearm -- which is why the SIU is mandated to investigate.
A 46-year-old man was apprehended under the Mental Health Act and transported to hospital.