London’s Heathrow airport closed due to major fire—causing worldwide disruption as over 1,000 flights affected

Britain's Heathrow airport -- Europe's busiest -- shut down early on Friday after a major fire at an electricity substation cut power to the sprawling hub, causing disruption worldwide to hundreds of flights and thousands of travellers.

Around 120 Heathrow-bound planes were in the air when the closure was announced, according to online flight tracking service FlightRadar24.

Around 70 firefighters were deployed to tackle the "highly visible" blaze at the substation in Hayes, west London.