American Airlines flights resumed early Tuesday after a roughly one-hour grounding caused by a technical issue, but stormy weather in the Dallas-Fort Worth area is causing additional delays for travelers.

Just before 6 a.m., the Federal Aviation Administration ordered all American Airlines flights grounded in the U.S. at the airline’s request. The Fort Worth-based airline had reported a technical issue affecting its entire system with millions traveling for the holiday.

The problem was a “vendor technology issue” that “briefly affected flights,” the airline said in a statement before 8 a.m. The issue impacted systems needed to release flights.

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

A post on the Federal Aviation Administration’s website acknowledged the airline’s request for a “nationwide ground stop” for all American Airlines planes and their subsidiary airlines. The ground stop lasted about an hour, according to the airline.

As of 9:55 am., flights departing from Dallas Love Feild were experiencing an average of a 30-minute delay due to thunderstorms, according to the FAA.

The groundings couldn’t come at a worse time for the millions of travelers expected to fly over the next 10 days.

A sign near the entrance to DFW International Airport warned of congestion at Terminal C, but at 8 a.m., one security checkpoint didn’t even have a line.

Several passengers who spoke to The Dallas Morning News said they hadn’t experienced any delays yet. A few were delayed about 60-90 minutes, but said they were unsure if it was because of the network glitch or the weather.

A ground stop at DFW International Airport was called after 7:30 a.m. for thunderstorms, according to the FAA. The weather-related stop, which could be lifted later Tuesday, could compound delays for American Airlines passengers.

One couple, Ben and Gail Young, decided they weren’t waiting around to find out. Their flight was only pushed back about 90 minutes, but Gail said they think there will be more delays.

“10:30 changed to 12:30 changed to 3:30 and you’ve been sitting here all day because the system gets backed up,” Ben Young said, adding that he used to work in the airline industry.

He added they hope to get a refund for their canceled travel.

Eric Par and his family experienced a delay in their travel plans as well, but they were unsure how it would affect the rest of their day.

Par said their flight was pushed from a 10:25 a.m. departure to 11:45 a.m. He said they would see what happens at 11:45 a.m. before making further choices.

By 10 a.m., most travelers who spoke with The News said they were unaware of any issues with their flights.

DFW International Airport was expecting its “busiest winter holiday season on record,” with an estimated 4.7 million passengers traveling through the airport from Dec. 20 to Jan. 7, according to a news release.

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