Four fire engines and 21 firefighters and officers dealt with a fire above a petrol station on White Hart Lane in Tottenham.
All the petrol pumps were isolated. Part of a first floor was damaged by the blaze.
Twelve people left before the Brigade arrived with one man treated for smoke inhalation. He is being treated at the scene.
The Brigade was called at 0822 and the fire was under control by 0904. Fire crews from Tottenham and Hornsey fire stations attended. The cause of the fire is under investigation.