Police say the shooters are among the dead, but only two of the deaths are considered homicides.
Const. Alex Li says the third death remains under investigation, with post-mortem examination results expected soon.
Police have said they found two guns at the scene of the shooting, which started inside a condominium that was being rented out through Airbnb and then spilled out into the hallway.
Li says Tyronne Noseworthy, 19, who performed under the name fourty4double0 with the TallUp Twinz, was shot and killed.
Jalen Colley, 21, and Joshua Gibson-Skeir, 20, both of Brampton, Ont., were identified as the two others who died.
A fourth person suffered serious injuries after being shot while a fifth person suffered minor injuries.
Police say they expect to update the public on the shooting once their investigation is complete.