The province's Special Investigations Unit has been called in after a man was seriously injured in a police-involved shooting in the heart of the downtown core early this morning.

According to the SIU, police received a call at around 5:30 a.m. about a man who was being attacked by another man armed with a knife on Yonge Street, north of Dundas Street.

Officers responded to the area sometime around 6 a.m. and confronted a 39-year-old man on Dundas Street between Bay and Yonge Streets.

“Several shots were fired and the man was struck a number of times. That man was taken to hospital. He underwent surgery and he currently remains in hospital in non-life-threatening condition,” SIU spokesperson Jason Gennaro told CP24. “The 66-year-old man who was part of the knife incident earlier sustained one knife wound. He was taken to hospital and released.”

The man who was shot by police is currently being held in custody while in hospital, Genarro said.

Gennaro said there is currently no information about what led to the initial conflict between the two men.

He said forensic officers are at the scene collecting evidence. Investigators are also canvassing the area to speak with possible witnesses and to find surveillance footage from area businesses so they can better understand what took place.

The agency has designated one subject officer and four witness officers in the investigation.

Gennaro said the SIU has assigned seven investigators and three forensic investigators to probe the case.

Dundas Street has been shut down between Yonge and Bay streets as the investigation continues. The area is expected to be closed for several hours into the afternoon.

The 505 Dundas streetcars are also diverting eastbound via Bathurst Street, College Street and Church Street. The 506 College streetcars will be diverting westbound via Parliament Street, Queen Street, and Spadina Avenue.

The SIU is an arm's length agency that investigates reports involving police where there has been death, serious injury or allegations of sexual assault.