Over 130 firefighters were summoned to the scene at the former Seven Gables Theatre in Seattle's University District Thursday.
Just before noon, callers reported flames coming from the vacant building and within 20 minutes of their arrival, fire officials told King5.com that the roof collapsed.
Three alarms were called as the fire engulfed structure that was named a landmark in 2017 by the City of Seattle Landmarks Preservation Board.
The fire was brought under control just after 2 p.m.
Neighbors told the television station that the squatters has been living in the building for months.
Watch raw video from the scene below.
