Atlanta: Hundreds of flights were delayed or cancelled at Hartsfield-Jackson Atlanta International Airport on Sunday as a power outage left passengers at the world's busiest airport stranded in darkened terminals or in aircraft idling on tarmacs.

The partial shutdown at the start of one of the busiest travel weeks of the year forced the Federal Aviation Administration to hold back flights bound for Atlanta. Departures were delayed as well because equipment inside terminals was inoperative, the agency said. The FAA flight control tower was operating normally.

Passengers wait in a dark terminal at Hartsfield-Jackson International Airport during the power outage. Credit:STEVE SCHAEFER

The cause of the outage, which occurred just after 1pm local time, was not immediately known, the airport said in a statement. It was working with crews from Georgia Power to identify the problem and fix it.

In response, United Air Lines, American Airlines and Southwest Airlines suspended operations to and from Hartsfield for the rest of the day.