The Knoxville Fire Department is battling a blaze at Mighty Muffler on Western Avenue, near Sanderson Road.
Officials say firefighters were called around 11:45 Thursday about a vehicle on fire in the building. That fire quickly spread to the structure.
One worker was sent to U.T. Medical Center to be treated for smoke inhalation. He told fire officials he was using a torch on the vehicle when he may have come in contact with a fuel line.
Western Ave is blocked between Sanderson Rd and Clifton Rd.
No other injuries are reported at this time.