Ten fire engines and 72 firefighters and officers were called to a fire at a row of shops with flats above in Brighton Road in Purley.
Part of the roof of the building was damaged by fire. Approximately 20 people left the buildings below before the arrival of the Brigade.
Station Manager Paul Cartwright, who was at the scene, said: "Our Control Officers received the first of a dozen calls about the fire at 1501. We quickly realised this was a large fire and made it up to 10 fire engines."
The Brigade was called at 1501 and the fire was under control at 1944. Fire crews from Croydon, Norbury, Sutton, Wallington, Addington and other surrounding fire stations attended the scene along with colleagues from Surrey Fire and Rescue Service.
The cause of the fire is believed to be accidental due to hot works being carried out.