A three-alarm fire tore through a historic building in the Junction on Thursday morning, causing significant damage to the structure.

The fire broke out at the vacant commercial building on Dundas Street east of Keele Street at around 3 a.m.

One man who works at a bakery across the street called 911. He told CP24 that crews arrived in less than a minute but were met by a fire that had engulfed most of the building.

“It was pretty big. It was coming out of the first window and then it came up to the second one. By the time they sprayed the water it was out of all of them (the windows),” he said.

Crews were able to knock down the fire by about 5 a.m. They were doing a room-by-room search of the building but had to evacuate at around 6 a.m. after part of a back wall began to collapse.

The building, which is a designated heritage property, dates back to 1890 and once housed the historic Peacock Hotel.

The cause of the fire is not immediately clear.

The Office of the Ontario Fire Marshal has been called in to investigate.