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 later told Reuters that all domestic flights departing from Dallas-Fort Worth, Chicago O'Hare and Miami had been halted.