In a move that disrupted holiday travel plans for thousands, American Airlines grounded all its flights across the United States on Tuesday due to an unspecified technical issue. The sudden suspension left passengers stranded at airports nationwide, with flights stuck on runways and returning to gates, as reported by Reuters.

The airline has yet to disclose the cause of the disruption. In response to inquiries on X (formerly Twitter), American Airlines said it was working to resolve the issue “in the shortest possible time” but did not provide a specific timeline.

A notice from the Federal Aviation Administration (FAA) indicated that the airline had requested a nationwide ground stop but did not elaborate on the reason. As of 7:30 a.m. ET, the airline had not issued an official statement on its social media platforms, communicating only through replies to individual users on X, Bluesky, and Facebook.

The disruption comes at a critical time as American Airlines, which operates thousands of flights daily to over 350 destinations worldwide, faced heightened demand ahead of the Christmas holiday. Shares of the airline fell 3.8% in pre-market trading following the announcement.

This incident echoes past airline tech failures, including a global outage linked to Microsoft’s Azure cloud platform earlier this year and a 2022 Southwest Airlines meltdown that resulted in nearly 17,000 flight cancellations and a record $140 million fine.

The FAA has not issued additional details, and American Airlines continues to work on resolving the situation, aiming to minimize delays for holiday travelers.