LONDON - Counter-terror officers from the Metropolitan Police are leading the investigation into a major fire that has closed London Heathrow Airport, a spokesperson said on Friday.

London Heathrow, one of the world's busiest airports, remains closed until midnight Friday due to a "significant power outage" caused by a fire at a nearby electricity substation.

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."

There was "currently no indication of foul play," but the spokesperson added that officers were retaining an "open mind at this time" regarding the cause of the blaze.

Flights have been canceled, 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 outage has affected the entire airport, with no clear timeline for power restoration. "To maintain the safety of our passengers and colleagues, we have no choice but to close Heathrow until 23:59 GMT on March 21," the airport spokesperson added.

National Grid posted on social media X that it had restored power to 62,000 customers by 0600 GMT, but some 4,900 homes remained without power.

The power is expected to be back on "in hours", but it was too soon to say exactly when this would be, according to the BBC.

Passengers are advised not to travel to the airport until further notice. Over 1,300 flights are affected on Friday, according to Flightradar24, a live flight-tracking website. Some planes have been diverted to other airports, including London Gatwick Airport, those in Paris, and Shannon Airport in Ireland.

British Airways, Heathrow's largest carrier, urged customers not to go to the airport until further notice and said it is working to update them on travel options.

The airport, which handled a record 83.9 million passengers last year, said its back-up diesel generators had "all operated as expected... but they are not designed to allow us to run a full operation".

Ofgem, Britain's energy regulator, announced it would commission a review "to understand the cause of this incident and what lessons can be learned."