The fire was reported Thursday at the Linwood Park complex on Edwin Avenue just after 4 p.m.
Residents could be seen from NewsCopter 7 using fire escapes on the building to evacuate their apartments.
"I was banging on people's doors begging them to come out and got as many of the elderly out as I could, I didn't even come out with shoes," one resident said who helped her neighbors escape.
The fire started in the basement and quickly spread because of the structure of the building. Emergency crews were working to keep the fire from spreading to a building next door.
"It spread quickly because of the architectural components in the building. They fought it as best they could - it's now out of control," said Fort Lee Mayor Mark Sokolich.
Firefighters were going door to door to make sure everyone was safely evacuated.
At least three volunteer firefighters have been injured so far but their injuries are not believed to be serious.
Officials said the Fort Lee Senior Center will serve as a shelter for residents.
It is unclear exactly what caused the fire.
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