Fire investigators are looking into what sparked an early morning apartment fire in East Ridge, Tennessee. The two-unit apartment caught fire around 4:30 a.m. on Castle Drive. Our crew was on the scene as East Ridge firefighters arrived to smoke and flames. Fire Department Corporal John Sentell described how it happened, "Around 4:27 we received a call about an apartment fire that was fully engulfed. We got multiple calls from neighbors. It's a two-story apartment on the front side and one story on the back. The back side is the actual side that caught on fire." Investigators are trying to figure out what caused the fire. Everybody got out and the building did have smoke detectors. "It was able to alert the family and everyone is OK," added Sentell.