Six fire engines and around 40 firefighters were called to a house fire on St Paul's Avenue in Harrow.
A terraced house was destroyed by the blaze. There were no reports of any injuries.
The Brigade was called at 0146 and the fire was under control 0315. Fire crews from Hendon, Millhill, Stanmore and Wembley fire stations were at the scene.
The cause of the fire is under investigation.