Firefighters remain at the scene of a three-alarm fire that tore through an automotive business in the Yorkdale area overnight.

The fire broke out at the plaza on Caledonia Road and Cartwright Avenue at around 4:20 a.m. and the building was quickly engulfed in flames.

Firefighters stamped out the blaze early on, but it flared up again and at around 8 a.m., crews resumed work to stamp out hot spots on the roof.

“There is a large volume of fire and smoke as a result of heavy fuel loads inside the building that includes vehicles, tires and other automotive related contents,” Toronto Fire said in a tweet.

The fire also affected a residential unit above the store, but no serious injuries were reported.

One female was treated by paramedics at the scene, but was conscious and breathing.   

The cause of the fire is not yet clear.

Chief of Fire Investigations Larry Coco told CP24 at the scene that investigators are waiting for the fire scene to settle before they enter to try and figure out exactly what happened.

“At present time crews are actively working on suppressing and containing some of the fires that have migrated,” Coco said.

He said firefighters struggled to put out extensions into the tar and gravel roof.

“We’re not going to commence the investigation until the fire is considered terminated,” Coco said.

At around 10:45 a.m., Toronto Fire said the fire had finally been put out.

Coco said investigators are also interviewing tenants in the complex to try and learn more about what was inside.

A stretch of Caledonia Road between Cartwright Avenue and Bridgeland Avenue is expected to remain closed for several hours as firefighters put out the blaze.