London's Heathrow Airport, one of the world's busiest airports, has come to a standstill after a significant power outage caused by a fire at a nearby electrical substation. The airport announced that it will remain closed until at least midnight on Friday, with no flights operating during this time, to ensure the safety of passengers and staff.

The power outage has thrown thousands of global flights into chaos, with 1,357 flights scheduled to land or take off from Heathrow today, according to flight tracking website FlightRadar 24. The airport, which handles an average of 220,000 passengers per day, is the busiest in Europe and ranked fourth globally.

At least 120 flights have already been redirected to alternative airports, with some flights from Toronto, Atlanta, Bridgetown, Barbados, Boston, Orlando, and Newark being diverted to Ireland due to insufficient capacity at London's other airports. Travel journalist Simon Calder told BBC News that this is the first time Heathrow Airport has been fully closed since the disruption caused by the Eyjafjallajokull volcano eruption in 2010.

Heathrow Airport has advised passengers not to travel to the airport until it reopens, with the airport stating that it does not have clarity on when power may be reliably restored. British Airways, the airport's biggest carrier, has also stated that the closure will "clearly have a significant impact on our operation."

The cause of the fire at the electrical substation, located about 1.5 miles away from Heathrow Airport, is currently unknown. The London Fire Brigade has brought the blaze under control after deploying 70 firefighters to the substation, and an investigation into the cause is underway. More than 16,000 homes in the area have also been affected by power outages.

The shutdown has left thousands of passengers stranded, with many taking to social media to express their frustration and disappointment. Images of an empty Heathrow Airport have also started to appear online, a stark contrast to the bustling airport that is usually filled with travelers.

The impact of the shutdown will likely be felt for days to come, with Heathrow Airport warning of "significant disruption" in the coming days. As the investigation into the cause of the fire continues, passengers and airlines alike are left waiting for news on when the airport will reopen and regular operations will be restored.

In the meantime, passengers are advised to contact their airlines for further information and to avoid traveling to the airport until it reopens. The shutdown serves as a reminder of the importance of robust infrastructure and contingency planning in the face of unexpected disruptions.