Counter-terror officers from the Metropolitan Police are leading the investigation into a major fire that has closed Heathrow Airport.
The force said there was “currently no indication of foul play” but officers were retaining an “open mind at this time” into the cause of the blaze.
Flights have been cancelled, people evacuated from their homes and local schools shut after two explosions and a fire at an electrical substation in Hayes, west London on Thursday night.
The airport, which is the UK’s busiest, has warned of “significant disruption” over the coming days and told passengers not to travel under any circumstances until it reopens.
The closure of London’s Heathrow airport due to a power outage is tipping one of the world’s busiest airports and the travel plans of hundreds of thousands of people into chaos.
The airport will be shut all Friday after a blaze at an electrical substation near Heathrow.
Disruptions would continue “over the coming days and passengers should not travel to the airport under any circumstances,” Heathrow said. The airport said it can’t say when power will be reliable restored. The fire service said the cause of the blaze wasn’t yet known.
Home to airlines including British Airways and Virgin Atlantic, Heathrow handles more than 1,400 flights and 200,000 passengers every day, and about 40 aircraft take off every hour at peak times.
The airport, by far the biggest in the UK, is a major hub for trans-Atlantic travel as well as connections into the Middle East and Asia.
A Met spokesperson said its Counter Terrorism Command was leading the investigation due to “the location of the substation and the impact this incident has had on critical national infrastructure”.
They added the command has the “specialist resources and capabilities” to progress the investigation “at pace to minimise disruption and identify the cause”.
Emergency services were first called to the scene at 23:20 GMT, and video shared on social media showed tall flames and smoke billowing from the substation overnight.
London Fire Brigade (LFB), which is also taking part in the investigation, said the fire involved a transformer containing 25,000 litres (5,500 gallons) of cooling fluid, which had been set alight.
Thousands of homes in the area were left without power as a result, as well as the airport.
National Grid said on X while it had restored power to 62,000 customers by 06:00, some 4,900 homes remained without power.
At least 1,351 flights to and from Heathrow will be affected on Friday, flight tracking website Flightradar24 said on X, with some 120 affected aircraft already in the air when the closure was announced.
The Energy Secretary Ed Miliband told BBC Radio 4’s Today programme it was an unprecedented event which “appears to have knocked out a back-up generator as well as a substation itself”.
Asked on BBC Breakfast how such a busy transport hub was able to be so severely disrupted by a fire at an electrical substation, he replied: “It’s too early to answer that question. We don’t know the cause of this fire.”
He said the government would want to understand the causes and “what lessons, if any, it can teach us”.
Ruth Cadbury, chair of the Commons Transport Committee, said the issue “does raise questions about infrastructure resilience”.
Ofgem, the energy regulator, announced it would commission a review “to understand the cause of this incident and what lessons can be learned”.
Ten fire engines and about 70 firefighters were sent to tackle the blaze, LFB said, with the fire being brought under control by 06:30.
A 200m (656 ft) cordon has been put in place as a precaution, and local residents have been advised to keep doors and windows closed because of a “significant amount of smoke”.
The brigade, which received nearly 200 calls about the fire, added it led 29 people to safety from nearby properties.
A group of residents who were evacuated from their homes gathered at a nearby Premier Inn but said there had been little communication overnight, leaving them confused about where to go.
Vaneca Sinclair, 64, said she was “getting ready to go to bed” when “suddenly there was this huge bang and the house just shook”.
“I thought maybe someone had crashed into the wall or something and then opened the front door… and there were just these flames everywhere down at the bottom of the road.”
She described the scene as “unbelievable – the flames and the smoke and everything… it was just scary”.
Ms Sinclair said police later told them to return home and grab essentials before evacuating, but no-one told them where to gather and eventually they walked to the hotel where they could have hot drinks and use the toilets.
“I’m absolutely shattered now,” she said.
Her neighbour Savita Kapur, 51, said she “literally just ran out of the house” when she heard the first explosion.
She said police officers told them to go back inside before eventually telling her she needed to leave.
“I have an elderly mother who is in her 80s and not very well at all – I had to escort her into my car and get her out of the area and drop her off to my sisters.”
Ms Kapur said a “second explosion went off” as she was driving along the road “and the whole ground shook”.
Hillingdon Council said in an update on its website: “Most evacuees have dispersed and have made arrangements themselves, and the council is assisting 12 people with hotel accommodation until it is safe to return to their homes.”
Four schools – Pinkwell Primary, Botwell House, Dr Tripletts and The Global Academy – are closed along with Nestles Avenue Early Years Centre and Pinkwell Children’s Centre.
The council said it would provide updates on whether any more local schools need to close.
Independent MP for Hayes and Harlington John McDonnell said he was “pretty shocked” and worried about the ongoing situation.
“There have to be questions asked about how the council reacted to this,” he said.
“I don’t want to be over-critical but I think they need to improve their performance. A lot of the residents didn’t feel very happy about not having information until quite late on.”
He added he hoped residents will be allowed back into their homes later on Friday and said he was told there would be a meeting for residents to update them.
A Heathrow Airport spokesperson said: “To maintain the safety of our passengers and colleagues, we have no choice but to close Heathrow until 23:59 on 21 March 2025.”
“We know this will be disappointing for passengers and we want to reassure that we are working as hard as possible to resolve the situation,” they added.
“Whilst fire crews are responding to the incident, we do not have clarity on when power may be reliably restored.”
The airport has apologised for the disruption and has advised passengers to contact their airlines for further information.
Heathrow is the UK’s largest aviation hub, handling about 1,300 landings and take-offs each day. A record 83.9 million passengers passed through its terminals last year, according to its latest data.
Several airlines with flights due to land at or take off from Heathrow have been cancelled or diverted to other airports.
Passengers have been advised to contact their airlines for the latest updates.
A family from Texas faced frustration after arriving at Heathrow for their flight home to Dallas to find the airport closed on Friday morning.
Andrew Sri, his wife, and their three children, aged one to eight, had been visiting his sister in east London.
“I just wish they had updated us accordingly,” Mr Sri said, as the family waited for updates at the terminal.
“Now we’ve got here and they told us, ‘actually the airport’s been shut down’, so it’s a little bit disappointing.”
By BBC News
Email your news TIPS to Editor@kahawatungu.com or WhatsApp +254707482874