American Airlines said its computers were back online after experiencing a widespread outage on Thursday, according to NBC affiliate WMAQ.
The Federal Aviation Administration first reported the outage and said only that the cause of the ground stop was "airline issues."
The airline took to Twitter to respond to customers on the matter.
American's stock was sharply higher in afternoon trading.
The FAA database said only that the cause of the ground stop was "airline issues." The database indicated the stoppage would last until at least 2:30 p.m. ET.
The airline told NBC affiliate WMAQ that it was working on resolving the issue but that it was it did not know how long it would take to resolve it.
A company spokesman said all domestic flights departing from Dallas-Fort Worth, Chicago O'Hare and Miami had been halted.
“We have resolved connectivity issues that led to a ground stop today at our Chicago, Dallas/Fort Worth and Miami hubs," said Alexis Aran Coello, a communications manager with American Airlines in a statement. "We apologize for the inconvenience and are working to get our customers on their way as soon as possible.”
Computers at O'Hare later reportedly started to come back online later, and only 10 departures had been delayed, WMAQ said later.
Click here for the latest on the markets.