It broke out around 12:30 am Tuesday at the shop at Belmont and Second.
Crews were called out for a vehicle burning in a back lot behind the building.
The flames then spread to multiple cars on the lot. That led to ruptured fuel tanks spilling gas on the ground.
Firefighters say there was also damage to the building itself.
The cause of the fire remains unknown.
Crews did say there were people sleeping inside the building, but said no one was awake when the fire started.