American Airlines operations are up and running again after technical problem grounded American flights

American Airlines flights were cleared to fly by regulators early Tuesday after a brief grounding due to a system-wide technical problem.

Just before 7 a.m. Eastern Time, the Federal Aviation Administration ordered all American Airlines flights grounded in the United States at the airline’s request. American had reported a technical problem affecting its entire system with millions traveling for the holiday.

In a social media response to frustrated travelers, the airline said: “Our team is currently working to fix this. Your continued patience is appreciated.”

The company has not issued a press release explaining the issue, and an email was not immediately returned.

A posting on the Federal Aviation Administration’s website acknowledged the airline’s request for a “nationwide ground stop” for all American Airlines flights and its subsidiaries.

The grounding came with millions of travelers expected to fly over the next 10 days.

The Transportation Security Administration expects to screen 40 million passengers over the holidays and through January 2.