Heathrow Airport in London was closed on Friday following a fire at a nearby electrical substation, causing a widespread power outage and leaving hundreds of thousands of travelers stranded.

Heathrow Airport said in a statement on X, “To maintain the safety of our passengers and colleagues, Heathrow will be closed until 23h59 on 21 March.” It added, "Due to a fire at an electrical substation supplying the airport, Heathrow is experiencing a significant power outage."

Heathrow Airport advised passengers not to travel to the airport and to contact their airline for updates, apologizing for the inconvenience.

London Fire Brigade sent 10 engines and 70 firefighters to tackle the blaze after the first 999 call at 11:23 p.m. Around 150 people were evacuated following a transformer fire in west London.

Reports suggest several flights have been diverted, with 669 scheduled to depart. Some US flights turned back mid-air and returned to their departure airport due to a lack of landing options.

Eurocontrol, the European Agency for Air Navigation Safety, has stated that no arrivals are being permitted at Heathrow Airport due to the outage.

London Heathrow, one of the busiest airports, served 83.9 million passengers last year, with a plane taking off or landing every 45 seconds. According to airport officials, Heathrow manages over 200,000 passengers and 1,400 flights daily.