Ten fire engines and around 70 firefighters tackled a fire on Norwood Road in Southall.
Half of the first floor and roof of a two-storey warehouse were damaged by fire. The roof was also damaged. Ten people were evacuated from the building by firefighters. There are no reports of any injuries at this time.
Local residents were been advised to keep their windows and doors closed due to smoke in the area.
A London Fire Brigade spokesperson said: "The fire has been producing a significant amount of smoke in the area and we asked local residents to keep their windows and doors closed and stay indoors where possible.
"Some road closures remain in place and we advise that drivers avoid the Norwood Road area due to heavy traffic congestion.
"The fire has been extinguished but firefighters are expected to remain on scene for much of the day putting out hotspots."
The Brigade's Control Officers received over 40 calls about the fire.
The Brigade was called at 0650 and Control Officers mobilised crews from Southall, Heston, Hayes and surrounding fire stations to the scene. A 32-metre turntable ladder is also being used at the scene as an observation tower, helping to provide the Incident Commander with a greater situational awareness of the incident.
The fire was brought under control by 0851.
The cause of the fire is under investigation by the Brigade and Metropolitan Police.