Toronto Fire is battling what it calls a "challenging" three-alarm blaze in an industrial building in North York.
No injuries have been reported.
Fire crews were called to the scene at Signet Drive and Kenhar Drive, near Weston Road and Steeles Avenue West, just after 2:30 p.m. It started out as a two-alarm fire, but was later upgraded.
Toronto Fire District Chief Stephan Powell said flames were seen coming through the roof as aerial operations and large volume hoses are being used to knock down the fire.
Powell said it's a possibility that the building might collapse.
Crews evacuated the building, including an adjacent unit.
The incident commander reported that "everyone is out of the building," according to Fire Chief Matthew Pegg in a tweet.
Due to the number of cars in the building, Toronto Fire brought in the Ministry of Environment for advice on fuel runoff.
Weston Road and Signet Road are closed between Fenmar Drive and Ormont Drive.