FULTON COUNTY, Ga. — Firefighters are working to determine what started a fire that caused nearly 20 people to lose their homes on Christmas Day.

Sandy Springs fire officials said early Monday that crews received reports of a fire at an apartment complex on Roswell Road.

When crews arrived, they found heavy flames coming from the structure.

According to fire investigators, all four units in the building were damaged by smoke and water, displacing 16 people.

No injuries were reported.

Crews determined the fire began in the building’s attic.

The official cause of the fire is under investigation.