Crews rushed to the Petrosyan Auto Repair shop on Blackstone near McKinley just after 9 a.m. Sunday.
They say smoke and flames were pouring from a detached building on the property.
Some gates surrounding the facility were locked, which momentarily delayed the attack but firefighters had the blaze under control within 20 minutes.
They tell us no one was inside the building at the time.
The exact amount of damage is not yet known.