Britain’s Heathrow Airport said it would be closed all of Friday after a huge fire at a nearby electrical substation wiped out power, disrupting flight schedules around the world.

Axar.az reports via Reuters, the London Fire Brigade said around 70 firefighters were tackling the blaze in the west of London, which caused a mass power outage at Heathrow, Europe’s busiest and the world’s fifth busiest airport.

Orange flames could be seen shooting into the sky. The fire brigade said the cause of the fire was not known.

“To maintain the safety of our passengers and colleagues, Heathrow will be closed until 23h59 on 21 March,” Heathrow Airport said in a post on X, adding that passengers were advised not to travel to the airport.

On the ground, a number of homes and businesses were without power. “Firefighters have led 29 people to safety from neighboring properties, and as a precaution, a 200-meter cordon has been established, with around 150 people evacuated,” the fire brigade said.

According to flight tracking website FlightRadar24, scores of flights were already being diverted to other airports, with Qantas Airways sending its flight from Perth to Paris and a United Airlines flight from New York heading to Shannon, Ireland.

Some flights from the US were turning around mid-air and returning to their point of departure.

Heathrow is one of the busiest two-runway airports in the world, with about 1,300 combined take-offs and landings a day, according to its website.