The blaze began in the basement, then ran up the walls and blew through the roof of one Harrison Street home shortly after 5 p.m.
An estimated 80 or so firefighters from Passaic and Bergen counties flocked to the scene as the blaze continued to burn past 7:30 p.m.
It was declared under control shortly before 8 p.m. No serious injuries were reported.
A total of 15 people in five families were affected, said Passaic Mayor Hector Carlos Lora, who was at the scene.
The city will do all it can to help them, he said.
An initial report of someone trapped in basement proved unfounded, responders said.
Firefighters were pulled from the building about 45 minutes into the blaze out of concern for a possible chimney collapse.
They continued battling flames from the exterior as the fire went from three to four alarms a short time later.
The cause couldn't immediately be determined. Investigators were requested to the scene.
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