Eight fire engines and around 60 firefighters were called to three vans alight on Lakeside Drive in Park Royal.
The vans were situated at the rear of a derelict office block and were completely destroyed by fire. Two single storey units and a small part of the external facade of the building were also damaged in the blaze. One man was treated on scene for burns and taken to hospital.
Station Commander Mick Palmer was at the scene, he said: "There was a lot of heavy smoke which prompted 32 calls to the Brigade's 999 Control officers. Fortunately only a small part of the external facade of the building was damaged in the blaze.
"Due to the smoke, local residents were advised to shut their doors and windows."
The Brigade received the first call to the fire at 1824. Fire crews from Park Royal, Wembley, Acton, Ealing and Willesden fire stations were in attendance. The fire was under control by 1937
The cause of the fire is undetermined.