An estimated 40 people were displaced from their homes Friday afternoon when a large fire tore through a Gwinnett County apartment building, officials said.

Crews responded to the Bridgewater Apartments along Ridge Brook Trail near Duluth about 5:30 p.m. after someone reported the building was on fire and two patios were engulfed in flames, Gwinnett fire spokesman Lt. Justin Wilson said.

Firefighters arrived to find a large blaze at the back of the building.

“Flames were quickly consuming the rear decks and extending into the attic space,” Wilson said, adding Gwinnett police went through the building and evacuated residents as firefighters tried to snuff out the flames.

Fire officials said the apartment’s maintenance staff also played an “integral role” in evacuating people, with one employee forcing their way inside a top-floor unit to get a resident out safely. Another man was able to get outside with his family and a few belongings after seeing the smoke and flames from his living room window, Wilson said.

Officials said a maintenance employee forced their way into a top-floor unit to evacuate one resident during the blaze.

Credit: Gwinnett County Fire and Emergency Services

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Credit: Gwinnett County Fire and Emergency Services

No residents or pets were injured in the blaze, but flames in the attic eventually caused the building’s roof to collapse. It took 45 firefighters about an hour to get the fire under control.

Investigators believe the fire started on a balcony, but said the building’s fire alarm system didn’t activate right away because of the location of the blaze. The exact cause of the fire remains under investigation.

Three units were destroyed and the two apartments beneath them sustained major water damage, Wilson said. Officials said about 40 adults and children were displaced from 19 units.

The American Red Cross was called to the scene and is providing temporary assistance to residents.