The fire broke out at one of the buildings on the 400 block of South Black Horse Pike in Blackwood, Gloucester Township around midnight.
Smoke filled the air with flames shooting from the roof of the A building of the Buttonwood Village Apartments.
"(I was) banging on everybody's door to let them know the fire was going on," said resident Chaquan Bundick. "It started from upstairs and it blew the whole top of the roof off."
Fire officials said while the fire burned through the roof, a firewall helped their cause by allowing crews more time to work. Firefighters initially had to pull back because the fire was too dangerous.
"The whole third floor is all the way down. Nobody's going back into the building, it's condemned," said resident Renee Lovisone.
The building is three stories with a basement in the lower level. More than 40 apartments are destroyed in building A of the complex, according to Blackwood Fire Chief Joe Cipriano.
"We credit that nobody was hurt or injured to all the residents helping everybody out," Cipriano said.
The 400 block of South Black Horse Pike was blocked in both directions out in front of the complex. It was reopened to traffic just before 5 a.m.
Officials said 29 people were left without homes on a cold January night. All of the residents of the building are accounted for, and those displaced were waiting and keeping warm on a bus provided by Camden County Emergency Services.
The Red Cross is assisting 29 people in 20 families with assistance for temporary lodging, food and clothing as needed.
There have been no injuries reported.
Fire investigators are still working to determine the cause of the fire.