A power cut at Atlanta’s Hartsfield-Jackson international airport has led to the suspension of outgoing flights and major delays.
It is not clear what caused the blackout, but firefighters say they are on standby as power company officials try to fix the problem.
Flights scheduled to arrive from other airports are being diverted elsewhere or held at their departure airport.
The outage has caused delays at security checkpoints and on runways.
In a statement, the airport said they sustained a power outage shortly after 13:00 (18:00 GMT) on Sunday and were investigating its cause.
The Federal Aviation Administration said flights bound for Atlanta had been being grounded and equipment in the terminals had stopped working.
Georgia Power, which provides electricity to the airport, said the cause of the power cut was not immediately known.
“Crews in the field are working with the airport to determine the cause as quickly as possible,” the company said on Twitter.
Images shared on social media showed passengers waiting in darkness.
Hartsfield-Jackson is the world’s busiest airport, handling more than 250,000 passengers and nearly 2,500 arrivals and departures every day.
Atlanta is located within a two-hour flight of 80% of the US population, making the city a major port of entry into the US and a common stopover for travel within the country.