In the first incident a man was shot and killed outside an apartment building on Denarda Street, just down the street from a daycare and just a few blocks away from the intersection of Weston Road and Eglinton Avenue West.
The victim, who has not yet been identified by police, was rushed to hospital without vital signs and later pronounced dead.
Police said 911 callers reported that the victim was in his 20s.
Neighbours who spoke to CBC News said they heard four or five gunshots fired just after 4 p.m.
The suspect is in the slaying is described as a tall male with a slender build. He was wearing a black hoodie and blue jeans, according to police.
A few hours later two people were shot on Falstaff Avenue, in the Jane Street-Highway 401 area.
One victim, a 20-year-old male, was shot several times in the torso in a stairwell at 40 Falstaff.
The second victims was found by EMS responders across the street, at a community centre at 17 Falstaff.
The 17-year-old male had been shot multiple times in the head.
Both shootings happened at about 8:10 p.m.
Police have not released any information about the identity of the victims, or any description of suspects.
Both victims taken to hospital, but there is no word on their condition.