The fire broke out around 11:30 PM on Thursday, and while firefighters battled through the night to contain it, part of the transformer building remains ablaze. Police have declared it a major incident, and investigations into the cause are underway.

By morning, the flames had been put out, but specialist crews continued working with breathing equipment to fully secure the area.

“This was a very visible and significant incident, and our firefighters worked tirelessly in challenging conditions to bring the fire under control as swiftly as possible,” said assistant commissioner Pat Goulbourne.

The airport’s closure due to a single substation failure has raised serious concerns. Heathrow officials have assured that backup power systems exist, but activating them takes time and is not an instant solution.

According to the Daily Mail, at least 1,357 flights have been canceled, delayed, or rerouted. Some planes already en route to London had to land at alternative airports, but with places like Gatwick now at full capacity, options are becoming increasingly limited.

As the situation unfolds, other European airports are preparing to accommodate flights that are too far along to turn back and must now be redirected.

Heathrow, one of the world’s busiest international airports, had a record-breaking January, welcoming over 6.3 million passengers—more than a 5% increase from the same period last year. This marked the 11th consecutive month the airport averaged over 200,000 passengers per day, with transatlantic travel being a major factor in the surge.

Adding to the travel disruptions, National Rail has confirmed that rail services to and from Heathrow will be canceled on Friday.