London, Mar 21 (AP) Hundreds of thousands of passengers faced flight cancellations at Europe's busiest travel hub after a fire knocked out power to London's Heathrow Airport, forcing it to close for the day.

At least 1,350 flights to and from Heathrow were affected, including several from US cities that were cancelled, flight tracking service FlightRadar 24 said.

Here's the latest: Heathrow says it doesn't know when power will be restored Heathrow Airport says it doesn't know when power will be restored and expects disruption to last for days after an electrical substation fire nearby.

The airport said in a statement it does not have “clarity on when power may be reliably restored.” It said it expects “significant disruption over the coming days and passengers should not travel to the airport under any circumstances until the airport reopens.” Heathrow earlier said the airport is not expected to reopen until Saturday.

Analysts say Heathrow closure raises worrying questions While the cause of the fire that shut down Heathrow Airport is still unclear, analysts say the incident raises concerns about the UK's ability to withstand attacks or natural disasters that damage critical infrastructure such as communications and power networks.

It's particularly worrisome given recent comments by Britain's security services that Russia is conducting a reckless campaign of sabotage across Europe, said Alan Mendoza, the executive director of the Henry Jackson Society, a London-based think tank focused on security and democracy in Europe.

“The UK's critical national infrastructure is not sufficiently hardened for anywhere near the level it would need to be at to give us confidence this won't happen again,” Mendoza said.

“I mean, if one fire can shut down Heathrow's primary systems and then apparently the backup systems as well, it tells you something's badly wrong with our system of management of such disasters,” he added.

European airline shares fall on main indexes The Heathrow disruption weighed on shares of European airlines, which posted declines that outpaced the fall in broader main stock indexes on Friday.

Shares of International Airlines Group, which owns British Airways, were down 1.4 per cent after falling as much as 3 per cent in early trading.

Shares of Lufthansa, which operates Germany's biggest carrier as well as Austrian Airlines, Brussels Airlines and others, fell 1.3 per cent. Air France-KLM, which operates the main carriers in France the Netherlands, slid 1.3 per cent.

German leisure and tourism company TUI, which owns five airlines including one that serves the British market, slid 1.8 per cent.

Other European airlines that don't operate at Heathrow were also dragged down by the negative sentiment. Wizz Air shares declined 1.4 per cent, easyJet was down 0.7 per cent and Ryanair dipped 0.8.

UK prime minister calls for rigorous investigation into fire The British government says “clearly there are questions to answer” about how a single fire could shut down Europe's busiest airport.

A spokesperson for Prime Minister Keir Starmer said there must be a rigorous investigation to make sure “this scale of disruption does not happen again”.

Tom Wells said the most pressing task is to extinguish the fire, which is still burning on Friday. He said that “at the moment the priority is to deal with the incident in hand”.

He said “it's very premature” to speculate on the cause of the blaze.

US flight operations normal as Delta issues waiver for Heathrow passenger Flight operations remained normal in the United States on Friday despite the Heathrow fire, according to the US Federal Aviation Administration.

Delta Airlines has issued a travel waiver through Sunday for customers who need to rebook their flights due to the Heathrow fire, a spokesperson said in a statement.

The company cancelled 10 flights scheduled to depart from Heathrow on Friday.

No indication of foul play in London blaze, police say Police say there is so far no indication of foul play in blaze that shut Heathrow but counterterror detectives leading the investigation into its cause.

The Metropolitan Police force says that is because of the location of the electrical substation fire and its impact on critical national infrastructure.

The force says counterterrorism command has “specialist resources and capabilities” that can help find the cause quickly.

Starmer thanks emergency services tackling blaze British Prime Minister Keir Starmer says he is receiving regular updates on the fire that has shut down Heathrow Airport, as he thanked the emergency services tacking the blaze.

Starmer posted on X: “I know the situation in Heathrow is causing distress and disruption, especially for those travelling or without power in their homes. I'm receiving regular updates and I'm in close contact with partners on the ground. Thanks to our emergency workers for keeping people safe.” Heathrow closure recalls Icelandic volcano disruption The Heathrow closure is drawing comparisons to the 2010 Icelandic volcano eruption that closed much of European airspace for five days out of fears volcanic ash could damage jet engines.

The eruption of the volcano Eyjafjallajokull (ay-yah-FYAH'-lah-yer-kuhl), after two centuries of silence, spewed an ash cloud that closed Europe's airspace and grounded millions of travellers. Iceland was briefly infamous as the country that stopped the world.

Read more about Iceland's tourism boom in the aftermath of the 2010 eruption.

Scandinavian Airlines cancels 12 round-trip London flights Scandinavian Airlines has cancelled all 12 of its flights to and from London Heathrow on Friday.

“We are closely monitoring the situation and remain in continuous dialogue with Heathrow. Naturally, we hope for a swift resolution,” the company said in a statement.

Known as SAS, it's considered the national airline of Denmark, Norway, and Sweden.

Hopes dashed for family seeking to travel home to Texas At Heathrow's Terminal 5, a family of five traveling to Dallas had shown up in the hopes their flight home — still listed as delayed — would take off.

But when Andrea Sri brought her brother, sister-in-law and their three children to the airport, they were told by police that there would be no flight.

“It was a waste of time. Very confusing,” said Sri, who lives in London. “We tried to get in touch with British Airways, but they don't open their telephone line until 8 a.m.” Other London-area airports could reroute stranded travellers Heathrow is one of the world's biggest airports, but there are five others in the wider London area as well.

Travellers might be able to rebook through the remaining five airports -- City, Gatwick, Luton, Stansted and Southend -- in the aftermath of Heathrow's closure.

However, they aren't all easy to reach from Heathrow. While City is in inner London, and buses link Heathrow with Gatwick, the others are further out. Southend is about a 78-mile drive from Heathrow, around the congested M25 orbital highway and then out to the eastern coast of England.

Witnesses describe fireball and loud explosion from substation blaze Residents in west London have described hearing a large explosion, followed by a fireball and clouds of smoke, when a blaze ripped through an electrical substation near Heathrow Airport.

Matthew Muirhead, who was working a night shift, said that at about 11:30 p.m. Thursday he saw smoke rising over trees, then “a bright flash of white and all the lights in town went out”.

Delivery driver Adeel Anwar said the heat and billowing smoke from the blaze were “absolutely apocalyptic.” He told Sky News that as he drove past the substation “I just felt the heat … I tried to just get out of the area as quick as possible.” Firefighters brought the blaze under control after seven hours and were still working to douse the flames on Friday. No injuries were reported.

Electricity supplier National Grid said power was restored to 62,000 customers by Friday morning, with 4,900 still without electricity.

Air India suspends Heathrow flights, with one turning around in midair All Air India flights to Heathrow were suspended until Friday midnight, the carrier said in a statement, adding that it will “update about resumption of operations as soon as we have more information".

The airline also said one of its flights had to return midair to Mumbai and another was diverted to Frankfurt. The company didn't specify how many flights were affected in total.

9 flights through Dubai cancelled after Heathrow closure Eight outbound flights from Dubai International Airport to Heathrow, and one inbound from London to Dubai, were cancelled on Friday, according to Dubai Airports.

Travellers were told to contact their airlines for rebooking options.

What should travellers do? Any travellers impacted by the Heathrow closure should contact their airline.

If a phone call doesn't go through, travellers can also try contacting the airline on social media.

Several airlines were responding to passengers' posts on social platform X on Friday. A representative for British Airways, for example, was telling customers on X to send a direct message to the airline's account so they could assist in rebooking.

For customers who are seeking a refund or other compensation, a European Union regulation known as EU261 could apply. Because the United Kingdom is no longer part of the EU, however, not every flight will be covered under EU261. The regulation covers flights within the EU, as well as flights departing from the EU to a non-EU country.

London flights from Barcelona and Madrid cancelled Spanish airport operator Aena said on Friday morning that 20 flights to and from Madrid and Barcelona had been cancelled due to the Heathrow power outage. A total of 54 flights headed to or departing from Spanish airports were affected.

In a post on X, the state-controlled commercial airport operator advised travelers to contact airlines for more information about disrupted flights.

An incredibly long day for travellers Lawrence Hayes was three-quarters of the way to London from John F. Kennedy International in New York when Virgin Atlantic announced they were being diverted to Glasgow.

“It was a red-eye flight and I'd already had a full day, so I don't even know how long I've been up for,” Hayes told the BBC as he was getting off the plane in Scotland.

“Luckily I managed to get hold of my wife and she's kindly booked me a train ticket to get back to Euston (railway station in London), but it's going to be an incredibly long day.” Ryanair adds rescue flights' between Dublin and London Stansted Ryanair has added eight “rescue flights” between Dublin and Stansted, another London airport, on Friday and Saturday to help travellers impacted by the fire at Heathrow, the budget airline announced.

Ryanair does not operate at Heathrow.

Four of the flights will occur Friday afternoon, and the remaining on Saturday morning.

Lufthansa Group cancels flights to and from Heathrow All flights by Lufthansa Group to and from Heathrow were cancelled on Friday.

The company didn't specify how many flights were affected in total, but said in an emailed statement that “passengers affected by the flight cancellations have been rebooked on other flights and informed about it".

Lufthansa Group includes Germany's biggest airline, Lufthansa, as well as Austrian Airlines, Swiss, Brussels Airlines and others.

No evidence that substation fire was suspicious, UK officials say British officials working to determine the cause of an electrical substation fire that shut Heathrow Airport have not yet found evidence it's suspicious.

Energy Secretary Ed Miliband says “it's too early to say” what caused the huge blaze, but there's “no suggestion” of foul play.

London's Metropolitan Police say the fire brigade is leading the investigation, suggesting it's not thought to be criminal.

Flights from Tokyo diverted or turned around The closure of Heathrow forced two Japanese flights that had already departed to return to Tokyo and a third to change its destination, airline officials said.

Japan Airlines said one of its two Heathrow-bound flights Friday returned to Tokyo's Haneda international airport, and another one diverted to the Finnish capital, Helsinki. A third flight out of Tokyo, operated by All Nippon Airways, another major Japanese carrier, also returned to Haneda.

Airline officials advised passengers to check the latest flight information for Saturday.

Birdsong replaces aircraft noise for Heathrow neighbours The noise from Europe's busiest airport is a constant bugbear for those who live nearby, but has temporarily fallen silent.

“Basically living near Heathrow is noisy. There are planes every 90 seconds or so, plus the constant hum of traffic, but you get used to it, to the point of no longer noticing," said James Henderson, who has lived next to Heathrow for over 20 years.

"Today is different. You can hear the birds singing.” Qantas diverts Heathrow flights to Paris Australian airline Qantas diverted its Singapore-London and Perth-London flights to Paris on Friday and then bused the travelers to London, a spokesperson said.

Customers will be contacted directly if their flight is impacted.

Aviation expert compares impact to 9/11 or Icelandic volcano Aviation consultant John Strickland says it will take several days for global airline travel to recover from a daylong closure of Heathrow Airport.

He said: “We're talking about several days' worth of disruption to get the planes recovered and start using them again to move planned and disrupted passengers.” Strickland compared the disruption to “a contained version of 9/11 or, to an extent, the Icelandic volcanic eruption” that shut European airspace in 2010.

“I remembered seeing on those occasions – particularly more so on 9/11 – it happened so quick and then US airspace was closed, they were turning back aircraft and holding planes. That's the parallel I would make.

“Heathrow being such a busy airport and full, there's no kind of wriggle room for getting out of these kind of things.” Heathrow closure has widespread impact on air travel The closure of Heathrow rippled through global aviation. The long-haul carrier Emirates in Dubai, which has London as one of its top destinations, cancelled six round-trip flights to Heathrow on Friday alone.

Etihad in neighbouring Abu Dhabi canceled two round-trip flights, while one flight diverted to Frankfurt, Germany. Qatar Airways said at least seven scheduled flights were “impacted”, with its staff working with passengers.

Blaze that shut down Heathrow is unprecedented, UK government minister says A British government minister says a “catastrophic” fire knocked out a backup generator as well as the electrical substation that supplies power to Heathrow Airport.

Energy Secretary Ed Miliband told the BBC that the blaze is “unprecedented”.

He said it's too early to know the cause but that lessons will have to be learned about “protection and the resilience that is in place for major institutions like Heathrow”.

Flights from Hong Kong rerouted to Amsterdam, airline says Hong Kong's Cathay Pacific Airways rerouted two overnight flights to Amsterdam and cancelled at least two daytime flights to Heathrow, according to the flight status page on its website.

Fire that closed Heathrow is now under control but not out The London Fire Brigade says the electrical substation blaze closed Heathrow Airport is under control.

The fire caused a widespread power outage, affecting thousands of homes, local businesses, and disrupting thousands of flights.

LFB Assistant Commissioner Pat Goulbourne says the fire was under control just after 8 a.m.

“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,” he said.

“Thanks to their efforts and a coordinated multi-agency response, we successfully contained the fire and prevented further spread.” Heathrow is one of the world's busiest airports Heathrow is one of the world's busiest airports for international travel. It had its busiest January on record earlier this year, with more than 6.3 million passengers, up more than 5 per cent for the same period last year.

January also was the 11th month in a row it averaged over 200,000 passengers a day, with the airport citing trans-Atlantic travel as a key contributor.

Heathrow normally opens for flights at 6 a.m. due to nighttime flying restrictions. It said the closure would last until 11:59 p.m. Friday.

The UK government earlier this year approved building a third runway at the airport to boost the economy and connectivity to the world.

Flights turn around as airport closes Seven United Airlines flights returned to their origin or diverted to other airports and its flights Friday to Heathrow were cancelled, the airline said.

The FlightAware website showed more cancellations including two from John F. Kennedy International in New York, a Delta Airlines flight and an American Airlines flight.

Other jets were diverted to Gatwick Airport outside London, Charles de Gaulle Airport in Paris and Ireland's Shannon Airport, tracking services showed.

National Rail cancelled all trains to and from the airport.

Fire cuts off power to Heathrow and thousands of homes Flames soared into the sky when a transformer at an electrical substation caught fire in west London late Thursday night. The fire continued to smolder after daybreak.

Scottish and Southern Electricity Networks said in a post on X the power outage affected more than 16,300 homes. About 150 people were evacuated.The cause of the fire is yet to be determined. (AP) PY PY