(CNN) Travelers stranded on planes on the tarmac for hours. Darkness in the terminal. Passengers guiding their cautious steps by the flashlights on their phones.
The power outage Sunday at Atlanta's Hartsfield-Jackson International Airport caused chaos, confusion and frustration, disrupting travel at the world's busiest airport. Power was restored late Sunday, minutes before midnight.
Travelers were greeted by darkness or dimly lit terminals. One traveler recalled the lights going off in the jetway as he disembarked from his flight from Boston.
The outage affected the sprawling airport's many restaurants, where employees told customers they had to pay cash
"I was like, 'Gosh, what's going on? It could be weather,'" Cierra Klett, who was standing in the security-check line when the lights started flickering, told CNN affilaite WGCL.
"Finally it went off, I was like, 'Oh no, like, it could be something way worse than just weather.'"
Rosemarie Frontero had just walked into the airport when the lights went out.
"At first, we were surprised and we were hoping the generators would go right in, it would kick back in, but now we don't know what we're going to do," said Frontero, who was heading home to New Jersey after attending her son's graduation at the University of Alabama.
As the hours ticked on, Frontero told WGCL everybody was waiting for somebody to explain what had happened.
"They're not saying anything. They're just saying that no planes are coming and no planes are going," she said.
Jessica Wine said she was stuck on a Delta flight from Houston for nearly four hours. Eventually, a crew brought moveable stairs to the plane, allowing passengers to deplane onto the tarmac, Wine said. Passengers walked to the stairs of the jetway and then through the dark passage.
Before she made it into the terminal, Wine, of Atlanta, told CNN by phone from the stopped plane that some of her fellow travelers were "getting a little agitated."
Overall, though, she said she was "really surprised how calm everybody is being because it's totally out of our control."
Crew members tried to keep people calm, bringing them water and snacks, while they waited for gate clearance, Wine said.
Wine said she saw food vendors walking up to the plane, hoisting boxes of water above their heads to crew members who reached out of the plane door to grab them.
With weak cell phone service and spotty wi-fi connections, Wine said some passengers had difficulty rescheduling their flights.
"I'm trying not to get stressed out about it. There is nothing any of us can do," Wine said.
Some outbound customers like Heather Kerwin of Atlanta didn't stick around for long.
Kerwin said she was dropped off at the lower entrance to the airport's south terminal shortly after 1 p.m. for her 2:30 p.m. New York-bound flight.
"It was completely pitch black," she said,
She recalled an officer telling her she might want to "use the light on your phone to see where you're going."
Kerwin said she used the flashlight on her phone to walk up the escalator. She saw "people crammed everywhere. Suitcases everywhere. Little kids crying near the ticket desks and kiosks.
On an already dreary, rainy day in Atlanta, the only light in the building filtered in from the windows.
At one point, passengers hushed each other to hear a Delta representative, who was trying to get travelers' attention by shouting, Kerwin recalled.
"There were a few emergency lights on but it was really dark -- felt totally apocalyptic. I decided to get the hell out of there," she said.