New York (CNN) — Following a brief outage that grounded all American airlines flights during one of the busiest travel periods of the year, American Airlines says it has resumed service Tuesday morning. American Airlines said a “technical issue” had delayed all of its flights in the United States. But the company began boarding flights again at around 8 am ET, airline spokeswoman Sarah Jantz told CNN. Flying out of Indianapolis International Airport? Check your flight status here. The Federal Aviation Administration lifted its nationwide ground stop order for all American flights. The FAA in a statement said American requested a nationwide ground stop but it referred all questions to the airline for more information. “We apologize to our customers for the inconvenience,” American Airlines said in a statement. David Myers, a 62-year-old disaster consultant traveling from from Salisbury, Maryland, to New Orleans with a layover in Charlotte said he was first alerted to the issue at 6 am Tuesday morning. He and his wife are trying to spend Christmas with their children. “It’s Christmas Eve, so complaining doesn’t seem quite right,” Myers told CNN. “And safety always comes first. But more information at the gate would be helpful.” Customers on social media began complaining early Tuesday morning that some flights were returning to their gates and that delays are about 90 minutes. “Captain says @AmericanAir software outage preventing weight & balance calculations ‘company-wide’ with no estimate on resolution. Flights unable to depart as a result. Not a good start to Christmas Eve travel!,” a person posted on X. In a video posted from Fort Lauderdale airport in Florida, an agent is heard saying “our system is down” and they are keeping passengers at the gate. American Airlines’ (AAL) stock initially fell nearly 3% in premarket trading, but rose 1% following the resolution.