Chattanooga firefighters responded to a fire at the Steak 'n Shake on Gunbarrel Road Monday morning around 4 a.m.
When officials arrived on scene, the fire was near the outside wall next to the front door.
After tearing into the exterior wall, the fire was extinguished in 15 minutes.
No injuries were reported.
The cause of the fire was ruled accidental, and likely the result of a discarded cigarette.