The shooting was reported to Toronto police just before 3:30 p.m. at 32 Wishford Dr., near Morningside Avenue and McLevin Avenue.
First responders arrived and found a 35-year-old victim wounded by a single gunshot. He was conscious and breathing when he was transported to Sunnybrook Health Sciences Centre.
Sgt. Doug Minor told reporters that police were still trying to sort out the precise sequence of events that led to the shooting.
"An altercation occurred and a shot was fired," Minor said Monday.
The victim was wounded in the neck. Minor said police have yet to recover a weapon.
There is "some indication" that the victim may have been on a TTC bus along with the suspect prior to the shooting, Minor said.
Minor said the suspect is described as a black male with his hair in cornrows, who wore a green hat with a red stripe on it, along with an Adidas shirt and baggy blue jeans.
Anyone with information is asked to contact investigators at 416-808-4200, or to call Crime Stoppers at 416-222-8477.