Four fire engines and around 25 firefighters were called to a fire at a house converted into flats on Barford Close in Hendon.
A garden shed was completely destroyed by the blaze and part of an extension at the rear of the property was also damaged by the blaze.
Two people left the property before the Brigade arrived. There were no reports of any injuries.
The Brigade was called at 0111 and the fire was under control by 0203. Fire crews from Hendon, Mill Hill and Finchley fire stations attended the incident.
The cause of the fire is not known at this stage.