Eight fire engines and around 60 firefighters tackled a fire at a school on Gordon Road in West Drayton.
The fire affected part of the roof and a range of solar panels. Around 550 pupils and staff left the building before the Brigade arrived. There are currently no reports of any injuries.
Control Officers took the first of 20 calls at 1215 and have mobilised crews to the scene from Hayes, Hillingdon, Feltham and surrounding fire stations to the scene. The fire was under control was 1404.
The fire is believed to have been accidental and was caused by the failure of a disused solar panel.