Ontario's Special Investigations Unit is probing the shooting death of a Pickering man after a TTC bus was pulled over by police in the city's east end Sunday afternoon.

Witnesses said a police cruiser blocked a TTC bus on Biscayne Boulevard, in the Eglinton Avenue and Victoria Park Avenue area, around 3 p.m.

Local resident Vincent Macleod said an officer got out of the cruiser as a young man emerged from the bus.

"The officer confronted him," Macleod told CTV Toronto. "The youth put his right hand in his left pocket, inside of his jacket, and as he did that the cop stepped back three steps, pulled out his gun and shot him three times."

The man, identified as 25-year-old Reyal Jensen Jardine-Douglas, was rushed to Sunnybrook hospital without vital signs.

Victoria Park Avenue, from Lawrence Avenue East to Biggin Crescent, was shut down as officers investigated the incident. A police marker was set on the ground where a knife had been left. Some witnesses reported seeing Jardine-Douglas holding a knife.

The victim's friend, Nicole Hemmings, told reporters Monday she was sad about the incident, "but it's not a big surprise."

When asked why, she would only say, "We always have a fear that this will happen when we want to get help."

She did not elaborate on what help the victim might have been seeking.

Joseph Markson, a lawyer for the officer involved in the shooting, released the following statement about the incident to CTV News:

"What I can say is that I believe that the actions of the subject officer stopped a potentially lethal threat to the lives of passengers on the bus and that he discharged his weapon in self-defence."

The special investigations unit investigates incidents where police are involved in deaths or injuries.

With reports from CTV Toronto's Tom Hayes and Austin Delaney