Chattanooga firefighters responded to an automatic alarm at Stoneridge Apartments at 1020 W. 37th Street at 3 a.m. on Tuesday.
Upon arrival, firefighters with Quint 14 were advised by some residents that there was a small fire in a vacant apartment on the second floor.
Battalion Chief Lesley Morgan said the building's sprinkler system activated, so all the firefighters had to do was basically stomp the remaining fire out with their boots.
Chief Morgan said the main damage was the water that leaked into the apartment below. Volunteers with the American Red Cross were called in to assist a family of five, because the power had to be disconnected from their apartment.
The cause of the fire is under investigation. No injuries were reported.