Ontario's police watchdog is investigating after police fatally shot a man near Spadina Road and Dupont Street on Wednesday night.

According to the Special Investigations Unit, Toronto police arrived at the scene around 9:15 p.m. after being notified of a man with a knife near 140 Spadina Road.

Shortly after, officers had an "interaction" with the man and he was shot by police.

Toronto EMS confirmed that another man in his 60s was stabbed in the neck during the same incident.

Both were rushed to St. Michael's Hospital, with the man who was shot pronounced dead a short time later.

Witness Ted Betts said he heard shouting beforehand and then a single gunshot.

"There were already police officers on the scene and ambulances on the scene, so there must have been some sort of incident leading up to that," he said.

The SIU investigates all incidents involving police in Ontario in which serious injury or death result. Four investigators and two forensic investigators have been assigned to probe the incident, the SIU said.

Toronto police closed Spadina Road between Dupont Street and Lowther Avenue, overnight for the investigation. The road has since reopened to traffic.