Fifteen fire engines and 97 firefighters and officers are dealing with a grass fire on Staines Road in Feltham.
Grass land the size of four football pitches is alight. Smoke from the fire has travelled near to Heathrow airport but it is not affecting their operations.
Fourteen horses were removed from a nearby field to a place of safety.
The number of resources are there to help with water relay.
The Brigade was called at just before 4pm on Saturday afternoon. Firefighters from Feltham and surrounding stations are at the scene. The cause of the fire is not known at this stage.