Officials believe the blaze began in the front of the building before spreading to other units.
All residents made it out safely, including 81-year-old Russ Hume, a former volunteer firefighter for nearly four decades. Hume said he called 911.
"Being a Lindenwold fireman, I've seen fires. I know what it's all about," Hume said.
Chopper 6 video of Lindenwold apartment building fire
He recalled hearing a noise just moments before discovering the flames.
"I walked out of my living room. I heard a popping. So, I went out on my balcony and I looked down and saw the flames coming out," he said.
About 60 volunteer firefighters responded to the Laurel Hill Apartments on Chews Landing Road around 11 a.m., the fire chief said. Neighbors watched as crews worked in the aftermath of a recent snowstorm.
"It's absolutely tragic. Seeing stuff like that you never want to see it, especially right after a huge snow storm," neighbor Ryan McCormick said.
Firefighters were able to rescue a cat, and Hume said they also managed to save some of his most meaningful belongings, including his first fire helmet.
"A lot of memories here, and they're all good guys - every one of them," he said.
Despite losing his home, Hume said he is grateful for what matters most. "Material stuff can be replaced. Saving a life is most important," he said.
McCormick praised the firefighters' efforts.
"Shoutout to those guys. They are true heroes. I got to see it firsthand today," he said.
Hume, who has survived cancer and dedicated decades to emergency service, said he hopes to return once the complex is rebuilt.
"I want to stay in this complex. It's nice and quiet. Everyone is friendly. Just a nice place to live," he said.
For now, he plans to stay with his daughter.
The American Red Cross is assisting the other displaced families. The fire chief said the cause of the blaze remains under investigation.