York Regional Police say they were called to a stretch of Yonge Street, just south of King Road, at 3:30 a.m., after a report that a male pedestrian had been struck.
Police received the call from the driver of black Honda Fit who reported striking a male pedestrian on the roadway.
But an investigation has determined the pedestrian was hit by another vehicle, which police are now looking for.
That vehicle is described as a silver, 2006-2010 R-class Mercedes SUV with front-end damage in connection to the incident. Police describe the vehicle as a crossover, more closely resembling a minivan than an SUV.
Finally, when a police cruiser arrived at the scene, it "came into contact with the same male on the roadway," according to a release from the Special Investigations Unit, which is now probing the circumstances.
The 30-year-old male victim has been identified.
However, since police are still in the process of notifying next of kin, his name has not yet been released.
The SIU investigates whenever someone is hurt or injured during an interaction with police, or when allegations of sexual assault are raised.