Toronto police were called to the eighth floor of an apartment building near McCowan Road and Highway 401 in Scarborough at around 6:50 p.m. on Sunday.
An altercation between a police officer and a 31-year-old man led to one of the officers using his firearm, according to the Special Investigation Unit's preliminary findings.
The man was taken to Sunnybrook Hospital for treatment of a gunshot wound.
This was the second shooting on Sunday which is being investigated by the SIU, after a shooting outside Musik nightclub in downtown Toronto.
Shooting inside the Exhibition Grounds
The SIU was called to the scene after the police-involved incident happened inside the Exhibition Grounds.
Investigator Derrick Wide said that the SIU believes that the first gunshot occurred early Sunday morning before police had arrived.
"The information we've received at this point and time is that at about 2:51 a.m., occupants that were at a local nightclub were leaving the nightclub… and there was an altercation in the parking lot area," Wide said in an interview with CBC News on Sunday.
According to Wide, gunfire ensued and two people were left wounded; a third suffered injuries not related to gunfire.
Officers patrolling the area arrived on the scene and had an interaction with a vehicle that had three people inside.
"The officers discharged their firearms… and the vehicle left the scene," Wide said.
Police caught up with the vehicle when it came to a rest in a snowbank on Dufferin Street. Two people were taken to hospital and a third was taken into police custody.
The SIU investigates all incidents involving police in which death or serious injury occurs, or when allegations of sexual assault are raised.