Firefighters from several towns responded to a four-alarm fire on Hale Street in Fitchburg on Friday night.
The fire was reported just before 5 p.m. and put out just before 7 p.m.
Heavy smoke and flames could be seen coming from a gaping hole in the roof and on all three floors of the building.
A home next door also caught fire after a wall collapsed onto it.
The Sentinel and Enterprise reports that the building was vacant. They say it was known as a place often occupied by the homeless, but it is currently unknown whether or not anyone was inside at the time of the fire.
There is no word on what caused the fire.
This week has been a busy one for firefighters across the state. Fire crews responded to three four-alarm fires in Barre, Lowell, and Lawrence on Thursday. A woman was killed in the Barre fire.