Watch: Eyewitness videos show towering flames at substation

Heathrow Airport is closing all day Friday due to a large fire that broke out at a nearby electrical substation in Hayes, Hillingdon.

The airport is experiencing a "significant power outage," a statement from Heathrow said.

"To maintain the safety of our passengers and colleagues, Heathrow will be closed until 23:59 on 21 March," it added.

"Passengers are advised not to travel to the airport and should contact their airline for further information. We apologise for the inconvenience."