Police are also looking into a possible connection between the three deaths and "an event" that took place in the city earlier in the day — although they weren't immediately releasing further details.
Local media reports say police are investigating a possible link between the bodies found in the apartment and an incident earlier in the day on a major highway that runs through the city.
The southbound lanes of Toronto's Don Valley Parkway were closed for hours on Saturday for a police investigation.
Homicide Det. Tam Bui says police expect to be at the apartment building where the three bodies were found for several days.