LOUISVILLE, Ky. (WDRB/AP) - Minutes after its midnight deadline to get the electricity back on at the world's busiest airport, Georgia Power announced early Monday that power had been fully restored to Hartsfield-Jackson Atlanta International, where more than 1,000 flights were grounded just days before the start of the Christmas travel rush.

Several flights to and from Louisville to Atlanta, Georgia, were canceled or delayed after the outage at the Atlanta Airport Sunday afternoon. A flight from Louisville to Atlanta scheduled for Monday morning was canceled.

According to the Atlanta airport's Twitter, the outage was reported around 1 p.m. Sunday, but the cause of the outage is still under investigation by airport and Georgia Power. 

A news release posted on the Twitter account said the FAA had issued a ground stop for flights headed to Atlanta, causing those planes to remain on the ground at their departure airports. Many inbound flights to the airport were also being diverted as a result of the outage. 

Meanwhile, the Louisville International Airport said on its Twitter account that delays were possible, urging travelers to stay up-to-date on the status of their flights. 

Louisville Airport spokesperson Natalie Chaudoin told WDRB just before 4:30 p.m. Sunday at least six Atlanta flights were impacted due to the outage. 

One departure to and one arrival from Atlanta had been canceled, and four additional Atlanta flights, two departures and two arrivals, were delayed, Chaudoin said. 

Chaudoin also said the status of those flights were subject to change anytime at the discretion of the airline, and that travelers with a scheduled flight to or from the Atlanta Airport should monitor their flight status on the Louisville airport's website or their chosen airline's website. 

Southwest Airlines canceled all scheduled flights to and from Atlanta on Sunday due to the outage. 

Several other airlines, such as Delta, also took to their social media accounts to make customers aware of the power outage, encouraging them to continue checking their flight status. 

The power was restored to the Hartsfield-Jackson International Airport around 1 a.m. EST Monday morning.

Georgia Power said on its Twitter page that "Power has been restored on all concourses. 5,000+ meals are being delivered to passengers. Trains will be operational soon."

Passengers at the airport were left in the dark when the lights went out at around 1 p.m. The outage halted all outgoing flights, and arriving planes were held on the ground at their point of departure. International flights were being diverted, officials said.

Hartsfield-Jackson, which serves 104 million passengers a year, is the world's busiest airport, a distinction it has held since 1998.

The airport serves an average of 275,000 passengers daily, according to its website. Nearly 2,500 planes arrive and depart each day.

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