The Alpha Auto and Air Conditioning Specialists on Belmont Avenue near First Street was heavily damaged by fire early Thursday morning.
Fire crews were able to knock the flames down quickly but say about half of the business sustained heavy damage.
The owner of the business, James Agazarian, arrived on the scene while fire crews were still mopping up and said the damage seemed to be contained to the older section of the building.
Agazarian also stated fire crews told him the fire appeared to have started in one of the vehicles inside the shop for service.
About one block of Belmont Avenue was closed while fire crews were at the location.
The cause of the fire is still under investigation.