An outbreak of severe weather, including thunderstorms, hail and intense winds, caused the cancellation of more than 400 flights and delays to hundreds more on Saturday at Hartsfield-Jackson Atlanta International Airport, the busiest in the world.

So far, The storms have caused 478 cancellations and 617 delays on flights to and from Atlanta, the airport reported.

The hardest hit airline has been Delta Air Lines, whose main hub is in Atlanta. Delta reported 542 canceled flights and 684 delayed flights nationwide on Saturday as it continues to work to return to normal operations following the impact of Friday's storms.

“Intense thunderstorms, including one that brought microburst winds and quarter-inch hail, caused more than 90 diversions to airports in the Southeast and a safety pause in operations on the night of June 27,” a Delta spokesperson said.

Aircraft inspection and ground stoppage

The airline said about 100 aircraft were inspected overnight for possible hail damage, and nearly all returned to service Saturday.

“Our people are working as safely and quickly as possible to resume flying,” Delta added, also thanking its customers for their patience.

Weather conditions forced the temporary suspension of all ground operations in Atlanta on Friday and the diversion of numerous aircraft flights.

Even the air traffic control tower that manages the space around the airport was briefly evacuated due to high winds, the Federal Aviation Administration (FAA) reported. Still, a skeleton crew of controllers remained to ensure air traffic management.

In recordings obtained from air traffic control, controllers were heard saying: We have evacuated due to weather, there are three people in the tower: controller, supervisor, and traffic management.

American Airlines also reported 223 cancellations in the US on Saturday, as it worked to recover from disruptions caused by severe weather on Friday at its Reagan National, Charlotte, and Dallas-Fort Worth locations.