The quartet was believed to be getting treatment for heat exhaustion, Passaic Mayor Hector Carlos Lora said from the scene of the fire on Union Avenue between Park Avenue and Spring Street.
One was brought out and rushed to the hospital by ambulance following a mayday call.
The extent of injuries couldn't be immediately determined.
Only one resident was in the house when the fire broke out on the first floor of the 2½-story wood-frame home and quickly spread around 3 p.m. July 12, responders said. He got out OK, they said.
An overheated air conditioner apparently was to blame.
Those living there "lost everything but their lives," Lora said.
Outdoor temperatures hit 92 degrees, forcing firefighters to rotate in quick shifts.
All of them were ordered out at one point for a quick head count before they returned to battling the flames.
The fire was officially placed under control shortly before 6 p.m., about three hours after it ignited.
Lora praised the city's firefighters and thanked companies from several neighboring towns in Passaic and Bergen counties who assisted either at the scene or in coverage.
These included firefighters at the scene from Clifton, Wallington, Paterson, Rutherford, East Rutherford and Carlstadt, as well as the Passaic County EMS Task Force and the County Wide Emergency Services Rehab Canteen.
A PSE&G crew was also needed to cut the power.
"It's the days that follow that become so challenging," the mayor said.
Thankfully no one died, he said, "but this family will need all the help they can get to rebuild."
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