The fire broke out right around 3 a.m. at the Brittany Commons development on Dunbarton Road in Mt. Laurel.
Flames were shooting out from one of the units when the first firefighters arrived, and the strong winds spread the flames quickly.
There were no injuries reported. Several of the units were destroyed and up to 20 units in the complex were damaged.
"There's at least 6 totally lost," said Captain Brian Aylesworth of the Mt. Laurel Fire Department. "Twenty in the whole building are affected, because the whole building, right now, is shut down."
Action News talked with Ashley Robinson, a resident who was among the first people to call in the fire.
"I smelled smoke, and thought somebody was using their fireplace," Robinson said. "Then about an hour later, my whole apartment was filled with smoke. And I opened the door, and the whole hallway was filled with smoke, and my neighbor's door was on fire."
After starting on the third floor, the fire was finally brought under control at around 4:30 a.m. Sunday.
"You had people out here running in nightgowns and robes," Mt. Laurel residnet Ken McGuire told Action News.
The American Red Cross is offering food and shelter to the 5 families who were left homeless by the flames.
Many residents are waiting to be let back in the building to salvage what they can.