Officials say the fire was placed under control by Monday evening, though firefighters were still putting water on hot spots Tuesday.
The 7-alarm blaze broke out around 3:30 p.m. on the first floor of a three-story structure at 3 North Warren Street in Dover. It is believed to have started in the basement of Barry's Luncheonette.
The building included stores on the first floor and apartments on the top two floors. The fire quickly spread to surrounding buildings.
At least 80 people were displaced, 40 of them permanently, and five buildings were destroyed.
Officials say 40 residents will eventually be able to return to their homes in adjacent buildings. The victims were moved from the firehouse to a community center.
Luckily, no injuries were reported.
Flames shot from the roof, while smoke billowed into the air and could be seen from miles away.
"This is a major structure fire," Dover Mayor James Dodd said. "It's a very difficult fire that they're fighting now. The buildings are old. They're doing the best they can right now to bring the fire under control."
WATCH Tuesday morning's briefing on the fire
Investigators discovered the fire was being fed by natural gas, which was shut down hours later.
Units from towns throughout Morris County were called in for assistance in battling the blaze.
"It's very, very difficult, it's very unfortunate," Dodd said. "It's devastating to the people that are losing their homes. That's our concern, and our local businesses, and we're going to do everything we can to help those people who were displaced."
Roads were closed off throughout the area.
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