Thousands of Delta Air Lines passengers were stuck in airports around the world trying to get out on flights Monday, after a power outage crippled the airline's global computer systems for hours.

Delta canceled more than 650 flights by the early evening. More than 2,000 were delayed, representing about one third of the airline's entire schedule.

In Richmond, Virginia, boarding passes were written out by hand. In Tokyo, a dot-matrix printer was resurrected to keep track of passengers on a flight to Shanghai. In New York, self service check-in kiosks were dark.

The company said travelers would be entitled to a refund for cancellations or serious delays. Travelers on some routes can also change their tickets free of charge.

"We apologize to customers who are affected by this issue, and our teams are working to resolve the problem as quickly as possible," the company said in a statement.

It noted that flight status systems, including airport screens, were incorrectly showing flights on time, something the company was trying to address.

Many passengers, like Bryan Kopsick, 20, from Richmond, were shocked that computer glitches could cause such turmoil. "It does feel like the old days," Kopsick said. "Maybe they will let us smoke on the plane, and give us five-star meals in-flight too!"

Early confirmation of the troubles first came in an official account that responds to customers via Twitter. The company had said its IT systems were down "everywhere."

The Atlanta-based carrier said the outage began at around 2:30 a.m. Eastern. Delta lifted its ground stop shortly after 8:30 a.m. Eastern but warned that travelers could expect significant delays and more cancellations. Flights in the air at the time of the outage were operating normally.

"Passengers become increasingly reliant on their ability to check in online (and) check their flight status," said Daniel Baker, CEO of tracking service FlightAware.com. "Not only are their flights delayed, but in the case of Delta the website and other places are all saying that the flights are on time because the airline has been so crippled from a technical standpoint."

People all over the world were affected. Stephen Smith, 32, of Baton Rouge, Louisiana, had been stuck on the ground for hours at Tokyo's Narita Airport on a flight that was supposed to go to Shanghai.

Smith took solace in the fact the air conditioning on the plane was working and said it seemed everyone on board was fine.

"Waiting game at this point," he tweeted to The Associated Press.

Computer outages are a periodic plague for airlines. Last month, Southwest Airlines canceled more than 2,000 flights over several days after an outage that it blamed on a faulty network router. Unions called for the airline to replace the CEO, but the board gave him a vote of confidence.

United has suffered a series of notorious delays since it merged with Continental as the technological systems of the two airlines clashed. Lines for British Airways at some airports have grown longer as the carrier updates its systems.

The Associated Press contributed to this report.