The fire was contained by Monday morning but there was still lingering smoke into Monday evening.
One firefighter suffered a minor elbow injury and several others were treated for smoke inhalation.
"We do believe the fire originated in a mattress factory and unfortunately then quickly spread to the surrounding factories, one of which was a cardboard factory," said Belleville Mayor Michael Melham.
One building contained huge helium containers which exploded as firefighters tried to knock down the fire.
Strong winds pushed the flames from the warehouse off Cortlandt Street to multiple nearby buildings, forcing families from their homes. Thick black smoke filled the sky and was visible for miles.
Firefighters from 40 to 50 departments responded to help Belleville firefighters for hours on end as they dealt with low water pressure Sunday. Wind also fueled the 12-alarm blaze.
Two homes close to the fire were destroyed and so was the new home of the Legacy Boxing Club, which was located in one of the buildings.
The Olympic style boxing training center served 80 to 100 kids in the community and the facility is a complete loss.
"Completely gone, we had two rings in there, we had 24 bags, we had everything the kids needed for training," said owner Yessenia Montalvo. "I have five more coaches that are now without a job, that's my concern, not me, but what we had in the community and the gym."
PSE&G re-energized power to neighboring streets after it was shut off Sunday, impacting the town hall and police department. Officials say 911 calls had to be rerouted to Nutley, New Jersey.
Officials also urged people to avoid the area and the fumes nearer the fire.
"Chemicals such as helium have been mentioned and that could contribute to the fire and the blaze and how extreme it's been," said Belleville Township Councilman Frank Velez.
Nearby residents were also urged to keep their windows closed, and use an air purifier if they have one.
"Your health is first and we don't want anybody to get caught in a place where they don't need to be and exposed to more smoke than we need to," Velez added.
Local public schools that were closed Monday as a result of the fire, will operate on a normal schedule with regularly scheduled start times on Tuesday.
School 9 will remain closed due to the ongoing situation, varying wind conditions, and out of an abundance of caution, according to Belleville Public Schools. Temporary arrangements have been put in place to ensure continuity for all students.
As for individuals or families that have been displaced, the Belleville Police Department said that they can go to the Friendly House, located at 20 Florence Street in Belleville, where the American Red Cross is set up and ready to assist.
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