Olatoyebi Waheed, 24, of Toronto, has been identified as the man who died at the scene.
A second man was wounded in the shooting, though police have not released his name.
Police say a post-mortem examination has determined that Waheed died from a gunshot wound to the chest.
On Monday evening, a suspect approached the Nissan Versa that Waheed was driving from behind, said Det.-Sgt. Hank Idsinga.
"A lone gunman approached from the rear of the vehicle and fired numerous rounds into the back and the driver's side of the Nissan vehicle, striking and killing the 24-year-old male who was driving the vehicle," Idsinga said.
Idsinga said the 23-year-old passenger was seriously injured in the shooting, though police expected he would survive.
The shooting took place in front of a TTC bus that was behind the vehicle that was targeted.
"I believe it was a targeted act at this point and time," Idsinga said, acknowledging that it could be a gang-related incident.
The shooting and homicide remain under investigation.
Anyone with information is asked to contact police at 416-808-7400. Tips can also be passed on anonymously through Crime Stoppers at 416-222-8477.