Alaska Airlines has resumed operations after an information technology problem forced hundreds of its flights to be grounded Thursday night.

A ground stop for all Alaska Airlines flights and flights of its subsidiary, Horizon Air, was lifted at 11:30 p.m. PT, the airline said in a statement. The ground stop was requested by the airline about eight hours earlier as the IT outage began, the FAA said.

“We are working to get our operations back on track as quickly and safely as possible,” the airline said, noting more than 229 flights had been canceled during the outage. “Additional flight disruptions are likely as we reposition aircraft and crews throughout our network.”

The airline did not immediately say what caused the outage.

One traveler in Austin, Texas, said the Alaska Airlines gates were “jammed” Thursday night as delays piled up.

“Some passengers have been allowed to leave the plane since it’s been over an hour,” passenger Mike Cully told CNN of a delay impacting his flight to Portland. “Crews here still with no update only to say that nothing has been officially canceled and they’re still counting on system to come back up,” Cully said on X.

Alaska Airlines had a similar outage in July and one after a systems upgrade in April of 2024.

Alaska is the fifth largest US airline and flies 44 million passengers each year to 120 destinations in five countries, accoring to its website. (CNN)