Six fire engines and around 40 firefighters were called to an industrial unit fire on Iron Bridge Road in West Drayton.
Part of the ground floor and most of the roof of an industrial unit were damaged by fire. The mezzanine level of the unit was destroyed by the blaze. Six people left the building before the Brigade arrived. There were no reports of any injuries.
The alarm was raised when a member of staff saw smoke coming from near the roof of the property and made the first of 11 calls to the Brigade.
Leading Firefighter Sam Maclean, who was at the scene, said: “On arrival, crews were faced with dark smoke and worked swiftly to stop the fire from spreading to adjoining properties.
“A 25-metre cordon was put in place as a precaution whilst crews worked to make the scene safe.”
The Brigade was called at 1156 and the fire was under control by 1415. Fire crews from Feltham, Heathrow, Southall, Richmond and Hillingdon fire stations attended the scene.
The fire is believed to be accidental but the cause has been recorded as undetermined.