Delta Air Lines reported early Monday that all its flights are grounded due to a worldwide computer systems failure.
"Our systems are down everywhere," the airline told customers via Twitter, according to the Associated Press.
"Flights awaiting departure are currently delayed," the airline said in a statement, according to CNN. "Flights en route are operating normally."
Delta operates 5,000 departures a day, Reuters reports.
Delta advised customers to check the status of their flights while it tried to fix the problem, CNN reported.
Widespread flight disruptions were reported by social media users. Thousands of Delta passengers around the world said they were experiencing delays.
Passengers reported delays at airports including London Heathrow, Tokyo and Los Angeles, NBC reported.
Delta's problems come less than three weeks after Southwest Airlines canceled more than 1,000 flights following a system outage.