A technical glitch early on Christmas Eve grounded American Airlines’ entire fleet of planes, setting up the potential for a domino effect of delays on one of the year’s busiest travel days.

The Federal Aviation Administration posted the advisory notice on behalf of the airline on Tuesday morning, saying in a statement that the nationwide ground stop was done at the airliner’s request. The apparent cause was a technical error that affected computer systems.

“Captain says @AmericanAir software outage preventing weight & balance calculations company-wide with no estimate on resolution,” one traveler wrote on X. “Flights unable to depart as a result. Not a good start to Christmas Eve travel!”

Another user posted a video on X from Fort Lauderdale Airport in Florida, in which the gate agent can be heard giving an announcement to the throngs of people waiting.

“We’re going to keep everybody in the gate area,” she can be heard saying. “…right now, our system is down. We cannot show the crew on or board any customers.”

The ground stop was lifted just before 8 AM Eastern, according to CNBC. It was not immediately clear what the source of the technical issue was or how many flights were delayed as a result.