Toronto Fire said the collapse occurred in the garage of a 14-storey high-rise residential building at 10 Tobermory Drive, just north of Finch Avenue.
Firefighters said some construction equipment was stored nearby, which may have caused the collapse.
One vehicle was damaged in the collapse.
Building inspectors and structural engineers head to the high-rise to check the integrity of the building.
Access to Tobermory Drive has been restricted for the past week as crews carry out trials for the new Finch West light rail system. Officials did not immediately confirm whether the roof collapse was related to that project.
