At least 13 people were left homeless after the fire gutted two buildings on Madison Avenue.
Eyewitnesses reported hearing a loud explosion before the fire started.
Authorities said it began in a two-story mixed-use building that has retail stores on the bottom level and apartments on the upper level.
Firefighters initially struggled to bring the blaze under control.
"The weather has been a big factor, I mean aside from it being cold, thankfully nothing is freezing, but the wind has really been whipping," Paterson Fire Chief Brian McDermott said. "Since the fire is exposing the attics, it's really taking the fire and pushing it in places where it's difficult for the firefighters."
There were no reports of injuries.
The city of Paterson is accepting donations for the families left homeless by the fire.
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