Four fire engines and around 25 firefighters were called to a fire at a taxi workshop on Cudworth Street, Bethnal Green.
Watch Manager Paul Rozan, who was at the scene, said: "The fire was discovered by a member of the public who noticed smoke coming from the back of the workshop and immediately called 999.
"Firefighters had to work quickly using specialist cutting equipment to cut away the door and tackle the fire to prevent it from spreading to neighbouring businesses."
Crews removed three propane cylinders and put them in a safe holding place as cylinders can explode when exposed to heat.
A small section of the workshop and three black cabs were damaged by fire. There were no reports of any injuries.
The Brigade was called at 0020 and the fire was under control at 0145. Fire crews from Bethnal Green, Whitechapel, Shadwell, and Shoreditch fire stations attended the scene.
The cause of the fire is under investigation.