Power has been fully restored at the Hartsfield-Jackson Atlanta International Airport after a complete power outage grounded flights Sunday afternoon, causing a holiday travel nightmare for fliers across the country just over a week before Christmas.

Kasim Reed, the city’s mayor, announced the power update on Twitter after the power outage forced the Federal Aviation Administration to suspend outgoing flights and implement a “ground stop” for incoming flights, which “means that flights headed to Atlanta are held on the ground at their departure airport.”

International flights were be diverted to other airports, U.S. Customs and Border Protection tweeted.

According to FlightAware.com, 1,174 flights have been canceled at Hartsfield-Jackson as of 9:30 p.m. ET.

A spokesperson told The Associated Press that no areas outside the airport were affected by the outage. However, flights at Chicago airports O’Hare International and Midway both have canceled flights — but it’s not yet clear if they were canceled due to Atlanta’s outage.

A massive power outage at Hartsfield-Jackson Atlanta International Airport has grounded flights Sunday afternoon.  (Instagram/chefforhire82)

Delta Airlines, which has its headquarters at the airport, said more than 900 mainline and regional flights were canceled, and 48 flights have been diverted to other airports. Delta tweeted that the airline issued a travel waiver for those “flying to, from or through Atlanta” and is “allowing customers to make one-time changes to their travel plans.”

Delta later announced Sunday that “approximately 300 flights will be cancelled” on Monday due to the power outage.

Southwest Airlines said they have canceled “all remaining operations” for the day, while an American Airlines spokesperson said three of the carrier’s flights have been diverted and there have been “a couple of cancellations.”