The fire broke out around 2:30 a.m. at a building on Van Dam Street and Nassau Avenue in Greenpoint.
Assistant Chief Wayne Cartwright told reporters the building is believed to be a woodworking facility.
“It was a heavy fire in the roof space. Due to a sagging roof condition, we quickly transitioned from an interior operation to an exterior operation,” he said.
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No injuries to firefighters or civilians were reported.
Residents were advised to close their windows to avoid the smoke, and drivers should expect street closures and delays in the area.
The fire marshal is on the scene and will investigate the cause.