The bodies were found inside a Thorncliffe Park apartment building late Saturday afternoon. Paramedics said they found two adults and one child, all without vital signs.
"Very sad news out of Thorncliffe this evening," tweeted Scott Gilbert, the superintendent of 53 Division. "Investigation is continuing. No suspects are currently sought for this horrendous crime."
Detectives are reportedly looking into the possibility the deaths are connected to what they're calling "an event" that occurred on the city's Don Valley Parkway earlier in the day.
The southbound lanes of the DVP were closed for several hours for a police investigation, creating traffic chaos.
Homicide detectives are expected to update their investigation later this morning.