Ten fire engines and around 70 firefighters were called to the scene of a fire at a block of maisonettes in Lyon Park Avenue, Wembley, overnight.
London Fire Brigade responded to calls at 1.57am and found the roof of the property and a neighbouring car workshop were alight.
The blaze was brought under control by 4.32am.
A force spokesman added on Twitter: "Fortunately there were no reports of any injuries."
Firefighters are likely to remain at the scene for some time as they work to extinguish any remaining hotspots.
Fire crews from Wembley, Park Royal, Acton, Northolt and surrounding stations were at the scene.
The cause of the fire is under investigation.
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