It wasn't immediately clear what sparked the fire in the city's East Ward, which broke out around 1 a.m. and was brought under control around 7:40 a.m.
Flames lit up the skyline of the Newark neighorhood when it first began.
It ripped through the roof of a three story building and quickly spreading to four neighboring buildings.
Two people were trapped inside.
"Firefighters were met with heavy fire and rescue conditions. We had to rescue several people out of the building," said Newark Fire Chief John Centanni.
The damaged buildings are a mix of both residential and commercial.
At least 55 residents are now without homes.
Sonia Valente's mother is one of those displaced residents.
Like many here, she is wondering when or if she will be able to go home.
"We don'tlknow what kind of damage is in the apartment," Valente said.
Heavy smoke and pockets of fire burned into the daylight hours as 85 firefighters struggled to get it under control.
Now investigators are trying to determine exactly how and what sparked this fire.
One resident and one firefighter were taken to the hospital and treated for minor injuries.
(The Associated Press contributed to this report.)