(CNN) — 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 Airl

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