Ontario's police watchdog is probing a fatal shooting involving police that happened after an armed robbery early Wednesday at Warden subway station.

Police responded to a 911 call just after midnight at the subway station in the east Toronto suburb of Scarborough.

CBC News overnight cameraman Tony Smyth reports the shooting happened at 682 Warden Ave., just south of the subway station, after a TTC fare collector was robbed at gunpoint.

Investigators say there was "an interaction" between police and a man near the station, and the 33-year-old man was fatally shot. The Special Investigations Unit (SIU) was called to the scene.

Eight investigators and three forensic investigators have been assigned to the case.

Warden station is closed Wednesday morning for the investigation.

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.

The shooting forced the closure of Warden station and some bus diversions for part of this morning's commute. The station was re-opened to traffic after 8 a.m.

With files from The Canadian Press