LONDON (AP) -- Delta Air Lines has grounded flights scheduled to leave 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 enroute are operating normally. We appreciate your patience.”

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.

Airline data company Flightaware said there were at least 858 cancellations and 7,359 delays across the global industry on Monday morning. It‘s unclear how many are related to Delta’s problems and whether Delta‘s groundings are reflected in the numbers.

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.