Firefighters responded to a fire at a hospital on Pond Street in Hampstead.
Part of a day ward was damaged by a fire involving a backpack. Around 40 people were evacuated by hospital staff before the Brigade arrived. Two men and four women assessed on scene for smoke inhalation by hospital staff.
The Brigade was first called about the fire at 1224, and the incident was over for crews by 1326. Firefighters from Walthamstow, Stoke Newington, Holloway and surrounding fire stations attended the scene.
The fire is believed to have been accidental, likely caused by the failure of a lithium battery in a rechargeable vape.