Heathrow Airport, the United Kingdom’s busiest airport, has been closed for the entire day following a fire at a nearby electrical substation, resulting in widespread travel disruptions for passengers worldwide. Over 1,300 flights have already been affected, and the number is expected to climb as the situation unfolds.

Flight tracking service Flightradar24 revealed that at least 1,351 flights to and from Heathrow were impacted. Passengers have been instructed not to travel to the airport until further notice as airlines scramble to manage the chaos.

The fire erupted at the North Hyde substation located about a mile and a half from the airport. Emergency services were called to the site around 23:23 GMT on Thursday. The London Fire Brigade reported that the fire was finally brought under control around 06:28 GMT.

As described by Energy Secretary Ed Miliband, the substation’s backup generator appears to have been compromised. Visuals shared on social media depicted significant flames and smoke billowing from the area throughout the night.

Local residents have been advised to remain indoors to minimize smoke inhalation, and several roads in the vicinity have been closed.

Authorities announced that Heathrow would remain closed until at least 23:59 on March 21. Passengers should expect significant disruptions moving forward as the airport does not know when power will be reliably restored.

Heathrow has already issued an apology for the inconvenience and is advising travelers to contact their airlines for the latest updates.

With over 1,300 flights affected, many travelers are feeling the impact, including the 120 flights that were airborne when the closure was announced. Alternative arrangements have seen some aircraft rerouted to neighboring airports, including Gatwick and Shannon. More than 16,000 local homes have also lost power, creating a larger disturbance in the community.

Travelers have been advised to stay away from Heathrow for the time being and to directly reach out to their airlines for further instructions. Virgin Atlantic has canceled all flights to and from Heathrow until midday on March 21. Other airlines, including United Airlines and British Airways, have also adjusted their schedules in response to these disruptions.

It is recommended that anyone planning to travel check the status of their flight and stay informed through official channels.