ATLANTA (AP) — The Latest on a power outage at the Atlanta airport (all times local):

6:50 a.m.

Passengers were being urged Monday morning to check with airlines for flight information as operations resumed in Atlanta following a power outage at the world’s busiest airport.

A tweet early Monday from Hartsfield-Jackson Atlanta International Airport said airport concessionaires and the security lines are open.

Georgia Power said a fire in an underground electrical facility caused a sudden power outage around 1 p.m. Sunday. That brought the airport to a standstill and grounded more than a thousand flights, leaving thousands of people stranded.

Power was restored around midnight.

Atlanta-based Delta Air Lines is the hardest hit airline. In a tweet, the airline urged travelers to use its mobile app or website for booking assistance and updated flight status. Delta was also allowing people traveling to, from or through Atlanta through Tuesday to make a one-time change for no fee.

4:10 a.m.

While power has been restored to the world’s busiest airport in Atlanta, the travel woes will linger for days.

Thousands of people are stranded Monday morning at Hartsfield-Jackson Atlanta International Airport, where more than 1,000 flights were grounded just days before the start of the Christmas travel rush.

A sudden power outage caused by a fire in an underground electrical facility brought the airport to a standstill Sunday about 1 p.m.

Delta, with its biggest hub operation in Atlanta, will be hardest hit.

Robert Mann, an aviation consultant and former American Airlines executive, said it likely will be Tuesday before Delta’s operations return to normal, and for passengers "it could be most of the week" because there aren’t many open seats on other flights in the last week before Christmas.