The man was pronounced dead at the scene in the Humberlea neighbourhood, the SIU said.
“Numerous” police officers and “several” emergency task force officers arrived along a stretch of rail between Weston Rd. and Highway 400, just south of Sheppard Ave. W., around 6:40 a.m., said SIU spokesperson Jason Gennaro.
Officers then tried to arrest the man at about 9 a.m. for trespassing under the federal Railway Safety Act, he said.
“There was a confrontation with a man. Shortly after, an officer discharged his firearm,” Gennaro said.
In addition to the police Glock pistol, a Taser was also fired.
Gennaro did not specify how many officers were involved but in a tweet Friday night, SIU stated “investigators have designated one subject officer and 15 witness officers.”
By afternoon, police tape stretched across what seemed to be a “makeshift shelter” along the tree-lined railroad. It sits directly across from St. Basil the Great College, a Humberlea-area high school, though officers said there was no threat to public safety.
Asked if there were any indication the man was living there, Gennaro said police were still investigating.
The SIU has launched at least two investigations so far this year into fatal shootings by Toronto police. Officers fatally shot a 30-year-old man and a 21-year-old man in two separate incidents last March, both near Bayview Ave. north of the 401.
The SIU is an independent civilian agency that investigates incidents involving police that result in death or serious injury. It invoked its mandate at 9 a.m. Friday, assigning seven investigators and three forensic investigators to the case.