It happened around 3:15 Sunday morning at Hunter's Garage on the unit block of South Harvard Avenue just off Route 70.
A passing motorist reported seeing flames shooting from the building.
Arriving fire crews went to work battling the blaze, which quickly went to a second alarm.
The fire was placed under control around 4:30 a.m. No injuries were reported.
Hunter's Garage has been in business for over 50 years.
The cause for the fire remains under investigation.