Firefighters rescued seven people following a fire at a shop with flats above in Finchley Road, West Hampstead.
Four fire engines and around 25 firefighters attended the incident.
Firefighters used a ladder to rescue four people from a first floor flat roof. They were treated on scene for smoke inhalation and one person was taken to hospital by London Ambulance Service.
A further three people on the ground floor were led to safety by firefighters.
Part of the ground floor was damaged by fire.
The Brigade was called at 0330 and the fire was under control by 0523.
Fire crews from West Hampstead, Kentish Town and Paddington stations attended the incident.
The cause of the fire is believed to have been electrical.