Delta Air Lines grounded flights scheduled to leave on Monday after experiencing unspecified issues with its computer systems globally.
Confirmation of Monday's troubles came in an official account that responds to customers via Twitter. The airline declined to immediately comment by phone and it was unclear whether all its flights were affected.
"Delta has experienced a computer outage that has affected flights scheduled for this morning," the Atlanta-based company tweeted to customers affected by delays. "Flights awaiting departure are currently delayed. Flights en route are operating normally. We appreciate your patience."
At Boston's Logan Airport, hundreds of people could be seen waiting in the check-in line.
An announcement made at the airport around 5:30 a.m. said passengers could check-in, but could not begin boarding their planes.
The company said its IT systems were down "everywhere" and "hopefully it won't be much longer."
Several applications were affected, including the company's website.
Among those affected by the situation is Stephen Smith, 32, of Baton Rouge, Louisiana. He has been stuck on the ground for about three 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.
Delta announced Monday morning they would offer waivers for all customers traveling on August 8 through August 12.
Computer outages have caused major headaches for airlines and travelers before. Southwest Airlines was forced to cancel more than 2,000 flights across the U.S. last month after technology problems prevented many travelers from checking in or boarding flights.
Travelers took to Twitter to share their frustrations with the delays.
By about 7 p.m., the airline reported that 3,340 of its nearly 6,000 scheduled flights had resumed. Its systems were back up and running but some delays and cancellations would remain into the evening.