United lifts ground stop after computer outage

United Airlines jet (Photo by Scott Olson/Getty Images)

United Airlines jet (Photo by Scott Olson/Getty Images)

All of United Airlines flights were grounded Sunday because of a computer outage, the Federal Aviation Administration said.

"A ground stop is in place for domestic flights due to an IT issue," United tweeted. "We're working on a resolution. We apologize for the inconvenience."

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The ground stop was lifted after 9 p.m.

"The ground stop has been lifted," United tweeted. "We're working to get flights on their way."

The Aircraft Communications Addressing and Reporting System, or ACARS, was having issues with low bandwidth, officials told NBC News.

International flights were not affected.

This is a developing story. Check back for updates.