London, United Kingdom (AFP) —Counter-terror police on Friday launched a probe into an electricity substation fire that shut down Heathrow airport causing travel chaos for passengers around the world and the cancellation or diversion of hundreds of flights from Europe’s busiest air hub.

Heathrow plies routes to around 80 countries and some 1,350 flights had been due to land or take off from the airport’s five terminals on Friday, according to the online flight tracking website Flightradar24.

Some 230,000 passengers a day and 83 million a year use Heathrow, making it one of the world’s busiest airports.

London’s Metropolitan Police said the force’s Counter Terrorism Command was leading enquiries given the “impact this incident has had on critical national infrastructure”.

“While there is currently no indication of foul play we retain an open mind at this time,” a spokesman added.

Firefighters were called to the “highly visible” blaze at the substation shortly after 2320 GMT on Thursday and around 70 were sent to battle the fire, which was brought under control by 0800 GMT.

UK Energy Secretary Ed Miliband promised that the government would do all it could to restore power to Heathrow quickly, as questions were raised about the airport’s “resilience”.

Electricity distribution network National Grid said around 1400 GMT that power had been partially restored to Heathrow as well as to local residents affected.

– Disruption –

The shut-down left many frustrated passengers struggling to make alternative arrangements.

“I had planned this journey three months ago… I’ve spent so much money on tickets and everything,” said Muhammad Khalil, 28, who was booked on a flight to Pakistan to be reunited with his wife after five months.

“You can’t imagine how stressful it is for me,” he told AFP.

British Airways said the closure of its main hub would have a “significant impact” on its operations and customers.

“We’re working as quickly as possible to update them on their travel options for the next 24 hours and beyond,” it said.

Talia Fokaides, 42, was supposed to leave London on Friday morning for Athens but rushed to Gatwick to get a new ticket when she heard the news.

Her mother was having open heart surgery later in the day.

“I just need to be there,” she told AFP, her voice shaking with emotion.

– Diverted –
Around 120 Heathrow-bound planes were in the air when the closure was announced, according to Flightradar24.

The UK’s second busiest airport, Gatwick, said it would accept some flights from Heathrow. Others were diverted to European airports including Shannon in southwestern Ireland, Frankfurt, and Paris Charles de Gaulle.

London Fire Brigade deputy commissioner Jonathan Smith said firefighters had worked “tirelessly in challenging and very hazardous conditions”.

He told reporters the fire had involved a “transformer comprising of 25,000 litres of cooling oil fully alight” posing a hazard due to the substation’s “still live high voltage equipment”.

One resident recalled hearing a “massive explosion” as the power cut out just before midnight while another reported seeing a “bright flash of white”.

Around 150 people were evacuated from nearby properties because of the fire.

The outage left 100,000 homes without power overnight with all except 4,000 restored by morning.

– Questions –

As the scale of the disruption began to emerge, Miliband faced questions about how one fire could shut down an entire airport.

He said National Grid had told him they had not seen “anything like the scale” of what happened.

“But it makes Heathrow look quite vulnerable and therefore we’ve got to learn lessons, as I say, about not just Heathrow but how we protect our major infrastructure,” he told ITV news.

Willie Walsh, director general of airline industry trade association IATA, said the closure was “yet another case of Heathrow letting down both travellers and airlines”.

“How is it that critical infrastructure — of national and global importance — is totally dependent on a single power source without an alternative,” he wrote on X.

“If that is the case — as it seems — then it is a clear planning failure by the airport.”

Flights from all over the world were affected by the closure and aviation consultant Philip Butterworth-Hayes told AFP it would cost “more than £50 million ($64.7 million)” to the airport and airlines.

Situated 25 kilometres (15 miles) west of central London, Heathrow’s main flight destinations last year were Dublin, Los Angeles, Madrid and New York.