NASHVILLE, Tenn. -- Investigators are trying to figure out what started a fire at a south Nashville apartment complex early Tuesday morning.

It happened at about 2 a.m. at the Winstead Manor Apartments off Edmondson Pike, near Southern Hills Medical Center. Fire crews said people living in an upstairs unit smelled smoke and called 911.

When firefighters arrived, they discovered a fire had started in the apartment below the callers.

Crews said before they could get to the fire, it burned itself out.

No one was in the apartment where the fire started. The unit suffered smoke damage but is not a total loss.