The fire broke out at the restaurant, at 215 S. Dunn St., around 5:30 a.m. Firefighters had extinguished the blaze and cleared the scene by 8 a.m.
The Mule City Grill was a total loss after the fire caused extensive damage to the building, firefighters said.
No one was injured in the fire.
Investigators said the origins of the fire do not look suspicious.