Heathrow Airport will remain closed until midnight following a major fire at a nearby electricity substation, which has triggered a widespread power outage.
The disruption is expected to affect at least 1,300 flights, including aircraft already airborne.
Passengers have been told not to travel to the airport, while all train services to Heathrow are suspended.
British Airways, the airport’s largest carrier, said the incident will have a “significant impact” on its operations and is working to update affected customers.
The fire broke out late Thursday at the North Hyde substation in Hayes, about one-and-a-half miles from Heathrow, leaving around 16,000 homes without electricity.
Ten fire engines and around 70 firefighters were deployed to tackle the blaze.
Emergency services have evacuated nearby residents and established a 200-metre safety cordon. The cause of the fire remains unknown, and efforts to restore power are ongoing.