Flames from the second-floor fire at Watson and Bridge streets quickly extended to the attic and first floor of the 2½-story building after the 1:30 p.m. call came in.
Eventually the roof collapsed.
A second alarm was called at the scene for additional manpower. Surrounding towns responded for mutual aid.
No injuries were immediately reported.
Anthony Michael Molnar contributed to this report.
Click here to follow Daily Voice South Passaic and receive free news updates.