What we know about the fire that brought London's Heathrow Airport to a standstill

LONDON (AP) — Heathrow Airport was up and running Saturday and airlines worked to clear the backlog after a fire at a nearby electricity substation knocked out power to Europe's busiest airport, disrupting travel plans for hundreds of thousands of people around the world.

The airport said it had made space for extra flights, but it is expected to take days to get stranded passengers to their destinations and displaced aircraft into the proper locations.

Here's a look at what happened and its impact on air travel.

A fire at an electrical substation in west London, about 2 miles (3.2 kilometers) from the airport, cut power to Heathrow Airport late on Thursday.

Residents reported an explosion and a fireball just before midnight. The London Fire Brigade said a transformer holding 25,000 liters (5,000 gallons) of cooling oil caught fire. It said 10 fire engines and 70 firefighters brought the blaze under control after seven hours, but isolated hotspots were still alight 24 hours after the fire started.

National Grid, which maintains energy infrastructure in Britain, said the blaze damaged equipment at the substation and cut power to 67,000 properties, including Heathrow. It said power was restored to all of them by Saturday morning.

The “significant power outage” initially forced Heathrow officials to announce that the airport would be closed until 11:59 p.m. on Friday, but some flights began to resume on Friday evening.

Officials said there was no suggestion of foul play, but the cause is still under investigation. The fire brigade said its investigation would focus on the electrical distribution equipment at the substation.

Even so, London's Metropolitan Police Service said counterterrorism detectives were leading the investigation because of the fire's impact on critical national infrastructure.

Energy Secretary Ed Miliband said it was "an unprecedented event.”

“Obviously, with any incident like this we will want to understand why it happened and what if any lessons it has for our infrastructure,” he told Sky News.

The closure disrupted the travel plans of around 200,000 people who were expected to travel through Heathrow on Friday. Heathrow advised passengers not to travel to the airport and to contact their airlines to rebook flights.

With all takeoffs and landings canceled, the first impact was on dozens of long-haul flights from North America and Asia that were in the air when the airport was shut down. Some were forced to turn around, while others were diverted to airports around the United Kingdom and Europe.

Heathrow-bound aircraft landed at Schiphol Airport in Amsterdam; Shannon Airport in western Ireland; Glasgow, Scotland; Manchester, England; Charles de Gaulle in Paris; Lyon, France; and Frankfurt, Germany, among others.

About 4,000 tons of cargo were also stranded by the closure, according to Anita Mendiratta, an aviation and leadership consultant.

The disruptions are expected to last for days as airlines move stranded aircraft and flight crews back into position and work to accommodate passengers whose flights were canceled. Mendiratta estimated that it would take two to four days to clear all the backlogs.

“This is an extreme situation where the entire aviation ecosystem is impacted,” she said.

“There will be two things that will be happening as a priority No. 1. First is airport operations and understanding, from an electrical system point of view, what has been impacted, if anything,” she said. “Did anything short out, for instance? What needs to be reactivated? And then how do you literally turn the airport back on again?"

Heathrow was Europe’s busiest airport last year, with 83.6 million passengers traveling through it. Its closure will have far-reaching impacts because it's a major hub for connecting flights to cities throughout the U.K. and around the world, as well as for travel to London.

Yes. Five other air hubs in southeastern England identify themselves as London airports, but they are much smaller than Heathrow. London Gatwick, Britain’s second-biggest airport, handled 43.2 million passengers last year. It's located in the town of Crawley, 28 miles (45 kilometers) south of London.

The fire raises concerns about the U.K.’s ability to withstand attacks or natural disasters that damage critical infrastructure such as communications and power networks, analysts said.

The incident is 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 security think tank.

“The U.K.’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,” he said. “I mean, if one fire can shut down Heathrow’s primary systems ... it tells you something’s badly wrong with our system of management of such disasters.”

Robin Potter, an expert on resilience at London-based think tank Chatham House, said that successive governments have been slow to respond to repeated recommendations from the National Infrastructure Commission to strengthen the ability of Britain’s power, communications, transport and water networks to withstand major shocks.

“We still have yet to see a kind of clear response from the government to those recommendations,” he said. “And we hope that maybe in the government’s upcoming resilience review, which we expect will be published at some point this year, it might seek to address some of those questions.”

Heathrow defended its response. Its CEO Thomas Woldbye said “the same would happen in other airports” faced with a similar fire.

A plane takes off as Heathrow Airport slowly resumes flights after a fire cut power to Europe's busiest airport in London, Saturday, March 22, 2025.(AP Photo/Kirsty Wigglesworth)

Passengers on a bus look at a parked plane as Britain's Heathrow Airport has closed for the full day Friday after an electrical substation fire knocked out its power, disrupting flights for hundreds of thousands of passengers at one of Europe's biggest travel hubs in London, Friday, March 21, 2025.(AP Photo/Kin Cheung)

Planes are parked at the Terminal as Britain's Heathrow Airport has closed for the full day Friday after an electrical substation fire knocked out its power, disrupting flights for hundreds of thousands of passengers at one of Europe's biggest travel hubs in London, Friday, March 21, 2025.(AP Photo/Kin Cheung)

This image taken from video shows parked planes at Heathrow airport, as a fire at the North Hyde electrical substation on Thursday night has led to a closure of Heathrow Airport in London, Friday, March 21, 2025. (Sky News via AP)

Omar Sheikh from Pakistan checks his phone whilst standing beside his lugage at Terminal 4 as Britain's Heathrow Airport has closed for the full day Friday after an electrical substation fire knocked out its power, disrupting flights for hundreds of thousands of passengers at one of Europe's biggest travel hubs in London, Friday, March 21, 2025.(AP Photo/Kin Cheung)

No travellers are seen inside Terminal 4 as Britain's Heathrow Airport has closed for the full day Friday after an electrical substation fire knocked out its power, disrupting flights for hundreds of thousands of passengers at one of Europe's biggest travel hubs in London, Friday, March 21, 2025.(AP Photo/Kin Cheung)

Smoke still rises as firefighters inspect the site of the fire at the North Hyde electrical substation, which caught fire Thursday night and lead to the closure of Heathrow Airport in London, Friday, March 21, 2025.(AP Photo/Kirsty Wigglesworth)

This image taken from video shows firefighters working to secure the area of a fire at the North Hyde electrical substation, which caught fire Thursday night and lead to a closure of Heathrow Airport in London, Friday, March 21, 2025. (Sky News via AP)

BEIRUT, Lebanon (AP) — Israel said it would respond “severely” to an attack from Lebanon after rockets were fired into northern Israel Saturday morning, a day after it vowed to increase the intensity of its operations in Gaza.

Israel's army said the intercepted rockets were targeting the Israeli town of Metula. This is the second time rockets have been fired from Lebanon into Israel since December, sparking concern about whether the fragile ceasefire with the Lebanese militant group Hezbollah would hold.

Hezbollah began launching rockets, drones and missiles into Israel the day after Hamas’ Oct. 7, 2023, attack out of Gaza ignited the war there. The Israel-Hezbollah conflict boiled over into an all-out war in September as Israel carried out massive waves of airstrikes and killed most of the militant group’s senior leaders. The fighting killed more than 4,000 people in Lebanon and displaced about 60,000 Israelis.

Under the ceasefire reached in November, Israeli forces were supposed to withdraw from all Lebanese territory by late January. The deadline was then extended to Feb. 18 by agreement between Lebanon and Israel.

But since then, Israel’s remained in five locations in Lebanon located across from communities in northern Israel and has carried out dozens of airstrikes on southern and eastern Lebanon, saying it attacked Hezbollah targets. Lebanon has appealed to the U.N. to pressure Israel to fully withdraw from the country.

On Saturday, Defense Minister, Israel Katz, said the country will not allow Lebanon to fire into Israeli communities. “We promised security to the Galilee communities and that is exactly what will happen,” he said.

There was no immediate comment from Hezbollah.

In a statement, Lebanon's Prime Minister, Nawaf Salam, asked the Lebanese military to take all necessary measures in the south, but said the country did not want to return to war.

The strikes come a day after Israel said it would carry out operations in Gaza “with increasing intensity” until Hamas frees the 59 hostages it holds — 24 of whom are believed alive.

Israel's military said Friday its forces were planning fresh assaults into three neighborhoods west of Gaza City and issued warnings on social media for Palestinians to evacuate the areas.

Also on Friday, Israel blew up the only specialized cancer hospital in the war-torn territory. The Israeli military said it struck the Turkish-Palestinian Friendship Hospital, accusing Hamas militants of operating on-site. Turkey, which helped build and fund the hospital, said Israeli troops at one point used it as a base.

Around 600 Palestinians have been killed since Israel relaunched the war earlier this week. Israel had already cut off the supply of food, fuel, and humanitarian aid to Gaza’s roughly 2 million Palestinians, aiming to pressure Hamas over ceasefire negotiations.

The international community has condemned the resumed attacks. In a statement Friday, the foreign ministers of the United Kingdom, France and Germany called Israel's strikes in Gaza a dramatic step backward. “We are appalled by the civilian casualties and urgently call for an immediate return to a ceasefire," they said in a joint statement.

The attack by Hamas-led militants in 2023, killed some 1,200 people and took 251 hostages. Most of the hostages have been freed in ceasefire agreements or other deals. Israeli forces have rescued eight living hostages and recovered the bodies of dozens more.

Israel’s retaliatory offensive has killed more than 49,000 Palestinians, according to the Gaza Health Ministry. It does not say how many were militants but says more than half of those killed were women and children. Israel says it has killed around 20,000 militants, without providing evidence.

Mednick reported from Tel Aviv, Israel. Associated Press reporter Kirsten Grieshaber in Berlin contributed to this report.

Follow AP’s war coverage at https://apnews.com/hub/israel-hamas-war

People walking surrounded by buildings destroyed during the Israeli air and ground offensive in the Gaza Strip are seen from southern Israel, Thursday, March 20, 2025. (AP Photo/Leo Correa)

FILE - Ronen Bar, chief of Israel's domestic Shin Bet security agency, attends a ceremony marking Memorial Day for fallen soldiers of Israel's wars and victims of attacks at Jerusalem's Mount Herzl military cemetery, May 13, 2024. (Gil Cohen-Magen/Pool photo via AP, File)

In this image made from a video released by the Israeli Government Press Office, Prime Minister Benjamin Netanyahu gives a statement Tuesday, March 18, 2025, in Tel Aviv, Israel. (Israeli Government Press Office via AP)

Palestinians carry bundles of wood as they walk along a beach road leaving northern Gaza during the renewed Israeli army offensive in the Gaza Strip, Friday March 21, 2025. (AP Photo/Abdel Kareem Hana)

Palestinians displaced by the Israeli air and ground offensive on the Gaza Strip sit in a makeshift tent camp inside a landfill in central Gaza Strip, Friday, March 21, 2025. (AP Photo/Jehad Alshrafi)

Israelis attend a rally against Prime Minister Benjamin Netanyahu's plan to dismiss the head of the Shin Bet internal security service, and calling for the release of hostages held by Hamas in the Gaza Strip, outside the Knesset, Israel's parliament in Jerusalem on Thursday, March 20, 2025. (AP Photo/Ohad Zwigenberg)

Demonstrators block a road during a protest against Israeli Prime Minister Benjamin Netanyahu's plan to dismiss the head of the Shin Bet internal security service, in Jerusalem on Thursday, March 20, 2025. (AP Photo/Ohad Zwigenberg)

Mourners carry the bodies of Palestinians including children who were killed by an Israeli army airstrike, at the Baptist Hospital in Gaza city, Friday, March 21, 2025. (AP Photo/Jehad Alshrafi)

A Palestinian man carries the body of his 11 years old daughter Aya Al-Samri who was killed by an Israeli army airstrike, during her funeral at the Baptist Hospital in Gaza city, Friday, March 21, 2025. (AP Photo/Jehad Alshrafi)

Displaced Palestinians, carrying their belongings and other items, move between southern and northern Gaza along a beach road away from the areas where the Israeli army is operating after Israel's renewed offensive in the Gaza Strip, in the outskirts of Gaza City, Friday March 21, 2025. (AP Photo/Abdel Kareem Hana)

Displaced Palestinians, carrying their belongings, wood and other items, move between southern and northern Gaza along a beach road away from the areas where the Israeli army is operating after Israel's renewed offensive in the Gaza Strip, in the outskirts of Gaza City, Friday March 21, 2025. (AP Photo/Abdel Kareem Hana)