Six fire engines and around 40 firefighters were called to a fire at a car showroom with a roof car park in Lombard Road in Battersea.
Four cars in the roof car park were destroyed by fire.
Two people were treated at the scene for slight smoke inhalation and were taken to hospital as a precaution by London Ambulance Service crews.
The Brigade was called at 0716 and the fire was under control at 0822. Fire crews from Battersea, Wandsworth, Chelsea, Clapham and Tooting fire stations attended the scene.
The cause of the fire is under investigation.