Upon arrival at the complex at 5500 Reunion Point around 1:30 p.m., firefighters reported smoke coming from an attic portion of a three-story building.
Within minutes, they were calling it a major working fire. Pictures from the scene showed the entire roof of the large building destroyed by the flames.
Witnesses told ABC11 that they saw smoke coming from the building and started knocking on doors to get residents out.
"We knew somebody had to be in there, and so we just started kicking doors in," said David Davis.
One man said at first he thought someone was cooking out.
"But it was too much smoke for a grill," he said.
No one was hurt in the fire that destroyed 12 apartment units and left about 25 homeless.
By 2 p.m., firefighters had the fire knocked down and were working to put water on hotspots.
Fire officials say the fire started in the attic, but the cause is unknown. Despite a rainy day, ABC11 meteorologists said there were no lightning strikes in the area.