Passengers disembark at New York's LaGuardia Airport on March 13, 2019. LaGuardia was among the airports affected by the computer glitch. (Frank Franklin II/AP)

A computer glitch is causing check-in delays for thousands of air travelers across the United States and Canada on Tuesday.

Sabre, a company that airlines use for reservations, printing bag tags and check-in, was experiencing computer issues, according to airline officials, and that is affecting the check-in process at multiple airports.

Sabre described the problem as “a system issue" that affected some of its customers, but said normal operations were returning Tuesday afternoon.

“Technical teams were immediately engaged. Customers are reporting normal operations,” its statement said. “We apologize for this inconvenience to those affected.”

Passengers reported outages in major hubs, including LaGuardia Airport in New York, San Francisco International and Fort Lauderdale-Hollywood International in Florida. Passengers faced long lines, and many reported wait times of more than two hours.

Officials with American Airlines said that the computer issues lasted only briefly and that they did not affect the carrier’s flights.

“Earlier today, Sabre had a brief technical issue that impacted multiple carriers, including American Airlines. This technical issue has been resolved. We apologize to our customers for the inconvenience,” the airline said in a statement.

In tweets to customers, JetBlue said airline crews were on the way to assist customers experiencing problems with online check-ins. A call for comment was not immediately returned.

In a tweet shortly after noon, the airline said: “All JetBlue systems are being restored following a temporary outage of Sabre’s systems which impacted multiple airlines. We apologize for the inconvenience. Please try again shortly.”

Passengers tweeted photos of long lines, with many growing frustrated as they were unable to get boarding passes. Some passengers also reported problems on the carriers’ websites and mobile applications.