Around 25 firefighters were called to a fire at a car repair workshop on Shield Road, Feltham.
A passer-by called 999 when they saw smoke coming from the main workshop door.
One car was destroyed by fire and a further two cars sustained fire damage. Firefighters removed two gas cylinders from the workshop and cooled them to ambient temperature as cylinders can explode when exposed to heat.
The Brigade was called at 1812 and the fire was under control at 2052. Two fire engines from Feltham fire station and two from Surrey Fire and Rescue service attended the scene.
The cause of the fire is believed to be due to an electrical failure within a car battery.