JetBlue planes at a gate at John F. Kennedy International Airport in New York.

"Systems are back online and customers are reporting normal or close-to-normal operations. We sincerely apologize for any resulting travel delays," said Sabre, a company that airlines use for printing tickets and making reservations.

Major U.S. airlines were hit with systemwide ticketing outages on Monday, which have since been resolved.

American Airlines said the technical issue was resolved shortly before 2 p.m. ET and had no major impact on flights. Alaska Air said on Twitter at 2:23 p.m. ET that its service was restored.

WestJet and JetBlue were also affected by the outage.

JetBlue said its customers could have issues with booking or check-in on its website, mobile app and in airport kiosks. "We are working to resolve the issue and apologize to our customers for the inconvenience," the airline said.

The cause of the outage wasn't immediately known. Sabre apologized for the disruption. "No downtime is acceptable," the company said.

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