One crew was initially called to a property in Cotswold Road after several reports were received a car was on fire.
The fire service said as firefighters arrived they discovered it had spread to the building.
Two more crews attended and helped fight the flames. The blaze is now out.
The fire was extinguished using four breathing apparatus, two high pressure hose reels and one water hydrant.
An eyewitness who lives down the road said they saw flames and smoke coming from the building.
Another said they saw masses of smoke as they left a shop in the town centre.
An ambulance was called as a precaution but no-one is believed to be injured, the fire service added.
Crews are still at the scene investigating.
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