Four fire engines and around 25 firefighters were called to a fire at a fish and chip shop on Camden Road in Camden.
Half of the ground floor was damaged by fire. Five people left the building before the Brigade arrived. One man was treated on scene by London Ambulance Service crews.
The Brigade's 999 Control Officers took nine calls to the blaze.
The Brigade's Fire Investigators believe the fire was accidental and involved a commercial deep fat fryer.
More information on using deep fat fryers safely
The Brigade was called at 1304 and the fire was under control by 1402. Fire crews from Wembley, Euston, Holloway and Paddington fire stations attended the scene.