London Fire Brigade are responding to a large fire at Middlesex Business Park in Bridge Road, Southall.
Residents in affected areas nearby are being evacuated, and schools have sent pupils home.
The Dominion Centre (UB2 4BQ) is being used as a rest centre for evacuated residents.
Disruption is expected from now until at least tomorrow morning.
Please avoid travelling via Merrick Road and all roads adjacent to it, including South Road, Bridge Road, and Havelock Road.
If you live nearby, please stay inside and keep windows and doors closed.