One of the busiest travel days of the year got off to a rough start due to a “technical issue” that disrupted American Airlines flights across the U.S.

The Federal Aviation Administration said early Tuesday that American Airlines requested a ground stop for all of its flights nationwide as millions hit the skies ahead of the Christmas holiday. A short time later, the agency announced that the nationwide ground stop had been canceled.

RELATED STORY | American Airlines suspends flights to Haiti indefinitely

“We have resolved a vendor technology issue that briefly affected flights this morning,” American Airlines said in a statement. “We sincerely apologize to our customers for the inconvenience and have issued a travel alert to allow for additional flexibility.”

This comes after numerous American Airlines passengers were posting on social media that their flights had been stopped on runways at various airports and were returning to their gates.

“We’re currently experiencing a technical issue with all American Airlines Flights,” the airline replied back to one person on social media. “Your safety is our utmost priority, once this is rectified, we’ll have you safely on your way to your destination.”

RELATED STORY | Flying home with your gifts? The TSA’s guide to having a smooth flight

American Airlines didn’t elaborate further on what may have caused the technical issue.

The grounding comes just months after a global tech outage sent airlines and other institutions into mayhem. The Cybersecurity firm CrowdStrike later said a bug in a software update caused the disruptions.