Four fire engines and around 25 firefighters were called to a garage fire on Sadler Close in Mitcham.
A domestic garage unit on the ground floor of a block of flats containing one vehicle was destroyed by fire. Around 50 people had left the building before the Brigade arrived. There were no reports of any injuries.
Heavy smoke logging affected the first and second floors of the property.
The Brigade was called at 0155 and the fire was under control by 0316. Fire crews from Mitcham, Wimbledon and Norbury fire stations attended the scene.
The cause of the fire is under investigation by the Brigade and the Metropolitan Police Service.