The Federal Aviation Administration (FAA) has lifted a nationwide groundstop of American Airlines flights in the US.

American Airlines grounded all its flights in the US earlier due to an unspecified technical issue, disrupting the travel plans of thousands of passengers set to fly out for Christmas Eve.

The company did not say why it was stopping all flights. Numerous passengers were posting on social media that their flights had been stuck on the runway at various airports and were now being sent back to the gate.

“An estimated timeframe has not been provided, but they’re trying to fix it in the shortest possible time,” the company said in a post on X, responding to a question from a stranded flyer.

Shares of the carrier were down 3.8% before the bell. A notice on the US Federal Aviation Administration website merely said the company had requested a nationwide groundstop, without giving a reason.

American operates thousands of flights per day to more than 350 destinations in more than 60 countries.

The grounding comes months after airlines were hit by a global tech outage tied to Microsoft’s Azure cloud platform and a software issue at cybersecurity firm CrowdStrike.

The US FAA was not immediately available for further comment.

Two years ago, Southwest Airlines experienced a meltdown with its systems during the holidays that led to 16,900 flight cancellations and stranded 2 million passengers. It was eventually fined $140 million in the largest-ever civil penalty for a travel disruption.