PHOENIX – A “technical issue” briefly disrupted American Airlines’ nationwide flights early Tuesday, the airline said, at the start of a busy Christmas Eve for travelers across the country.

The Federal Aviation Administration said American had requested a grounding of all of its flights. An hour later, American said flights would resume and the FAA lifted the nationwide ground stop.

“An issue with the provider’s technology briefly impacted flights this morning,” American said in a statement sent to ABC News. “The issue has been resolved and flights have resumed.”

“We sincerely apologize to our customers for the inconvenience this morning,” the statement continued. “It’s all hands on deck as our team works diligently to get customers where they need to go as quickly as possible.”

The airline reported “a technical issue on all American Airlines flights” in a post to X early Tuesday.

The post added: “Your safety is our top priority. Once this is fixed, we will get you safely on your way to your destination.” In response to questions from other social media users, the airline said it could not estimate how long the repairs would take.

The airline wrote that there is no “timeframe” yet, but they are “trying to resolve the issue as quickly as possible.”

In a statement sent to ABC News, the airline added: “Our teams are working to resolve the issue as quickly as possible and we apologize to our customers for the inconvenience.”

The ground stop is still impacting flights at Phoenix Sky Harbor. There have been 40 delays at the airport in the past 24 hours, and according to the airport’s website, the vast majority of delays affect American flights.

The disruption will be unwelcome for a record number of Americans expected to travel this holiday season. The Transportation Security Administration said it expects to screen nearly 40 million travelers from Dec. 19 to Jan. 2, a 6.2% increase from 2023.

American Airlines said Dec. 27 and Dec. 20 would be its busiest and second-busiest days, respectively, during the holiday season, which began Dec. 18.