Horrified onlookers tried in vain to stop a TTC streetcar that dragged a man for about 500 metres in Toronto's west end Tuesday, leaving him dead.

"A pedestrian became lodged underneath a streetcar. The streetcar driver had no knowledge of what was happening at the time," said Sgt. Ken George of the Toronto police traffic unit.

"Some citizens observed this poor victim being dragged along (and) flagged down some passing police officers who were on bicycles. They were able to catch up to the streetcar and get (it) stopped," he said.

"Unfortunately, it was too late for the victim, who was deceased because of his injuries of being dragged along here."

George said the victim appeared to be a white male, about 50 years of age. Police are trying to identify the victim, he said.

Emergency Medical Services confirmed a man was killed after being struck by a streetcar along Queen Street at around 10:30 a.m.

The man likely came in contact with the westbound streetcar east of Bathurst Street.

The streetcar stopped at Claremont Street, meaning the victim was dragged about 500 metres. George said the victim was found under dual sets of wheels at the rear of the articulated streetcar.

A woman who had been on board the streetcar at the time of the incident told CTV Toronto that she saw a police officer waving toward the TTC driver moments before he or she stopped.

Bystander Wallace Maitland said he spotted what appeared to be a bunch of rags under the streetcar's back wheels. "And then I saw an arm come out," he said.

Queen Street was closed west of Bathurst Street to Niagara Street during the police investigation. Pedestrians were also kept from the area. The scene finally re-opened to traffic around 5 p.m.

With a report from CTV Toronto's Michelle Dube