A two-alarm fire has caused significant damage to an abandoned building in Chinatown.

Crews responded to the scene on Spadina Avenue, north of Dundas Street West, around 2 a.m. Thursday.

The fire quickly spread throughout the structure, and witnesses said they saw flames shooting out the windows.

There are signs squatters might have been living in the building, but there are no reports of any injuries.

It’s not yet known how the fire started.