Four fire engines and around 25 firefighters were called to a fire at an office block on The Vale, Acton.
Part of the roof was damaged by fire. Five people left the building before the arrival of the Brigade.
The Brigade was called at 0019 and the fire was under control at 0238. Fire crews from Acton, Chiswick and Hammersmith attended the scene.
The cause of the fire is believed to be accidental and due to hot works being carried out on the roof.