The fire broke out around 7 A.M. Tuesday at the Smokin' Grill. That's a popular steakhouse in Grayson. That's in Carter County.
At least 65 firefighters battled the fire, but they weren't able to save the building.
A man on his way to work saw the fire, and stopped to capture it on his camera.
The building was the Western Steer restaurant for decades, and had just changed names back in November.
An arson investigator was on the scene this afternoon. Officials say it could take a couple of days before we know the cause of the fire.
The restaurant's owners have not yet said if they'll rebuild.