Dec. 18 (UPI) -- Officials restored electricity to Atlanta's Hartsfield-Jackson International Airport early Monday, but not before more than 1,000 flights were scrapped -- fueling fears that more holiday travel trouble could be coming.
The massive power outage began at the airport -- consistently ranked as the world's busiest -- on Sunday afternoon. Control towers, reservations and baggage operations, restaurants and concourse lighting were all affected.
Many passengers spent the night sleeping on terminal floors after standing in lines throughout the day. Some stayed aboard airplanes for hours before they were allowed to deplane.
Power was restored early Monday, but residual trouble from the outage is having an impact on air traffic across the United States -- largely because Atlanta-Hartsfield is a major hub for Delta Air Lines and a secondary hub for Southwest, American, United and other carriers.
A statement from Georgia Power said "switchgear located in an underground electrical facility could have failed and started a fire."
"This fire was located adjacent to redundant circuit cables and switching mechanisms serving the airport and those cables were damaged, resulting in the outage and loss of redundant service methods," the utility said.
Flights were detained not only in Atlanta, but to and from other cities, as well. Some were rerouted to airports with customs and immigration facilities.
The fire at Atlanta-Hartsfield International Airport came as the airline industry and passengers were deep into the start of a busy holiday travel period. With many flights full, few seats are available on later flights.
Experts said it could take days before normal service resumes. Atlanta's airport handles more than 100 million passengers every year, with about 2,500 arriving and departing flights per day.
Atlanta Mayor Kasim Reed said there was no indication that he fire was deliberately set, and noted the city's convention center was open to stranded passengers.
Delta on Monday announced a temporary embargo on travel by unaccompanied minors still at airports due to the outage. The Atlanta-based airline canceled about 900 of its flights by 7:15 p.m. on Sunday, and then its entire flight schedule from the airport. Southwest scrapped 70 of its 120 scheduled flights from Atlanta on Sunday.
Nearly 1,100 flights to or from Atlanta were canceled by Sunday evening, and FlightAware.com reported 1,285 flight cancellations and nearly 3,100 delays nationwide.
Delta worked to arrange free hotel accommodations for passengers stranded in Atlanta, and was among several airlines that began waiving fees to change flights.