No flights will arrive or depart at London Heathrow Airport (LHR) after the U.K. hub was forced to close following a fire at the nearby power station.

The airport will be closed on Friday until at least midnight while power is restored and contingency plans are implemented.

“Heathrow is experiencing a significant power outage across the airport due to a large fire at a nearby electrical substation,” said a Heathrow spokesperson. “Whilst fire crews are responding to the incident, we do not have clarity on when power may be reliably restored.”

“To maintain the safety of our passengers and colleagues, we have no choice but to close Heathrow until 23h59 on 21 March 2025.” the spokesperson added.

Heathrow said they expect “significant disruption” over the coming days and that passengers should avoid traveling to the airport “under any circumstances” until the airport officially reopens.

Heathrow is the second busiest airport in the world and was due to see over 1,330 scheduled flights today, according to data from aviation analytics firm Cirium. Up to 291,000 passengers could be affected on Friday alone, and the knock-on effects over the weekend are likely to be significant.

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British Airways has the largest share of flights (51%) scheduled to take off from LHR today, followed by Virgin Atlantic and Lufthansa.

It is unclear how many of the scheduled flight operations will be canceled and how many may be diverted to nearby airports. As of 8:10 a.m. (GMT), at least seven flights scheduled to land at LHR had been diverted to London Gatwick Airport (LGW).

“We are aware of the situation at Heathrow Airport today and we are supporting by accepting diverted flights as required,” a London Gatwick spokesperson told TPG. “Flights are operating from London Gatwick as normal today.”