CHICAGO (CBS) —American Airlines said it has fixed computer problems that caused major delays at O’Hare International Airport and two other major airports Thursday afternoon, and was working to get its flights back to normal.

 American Airlines flights at O’Hare International Airport have been grounded Thursday afternoon, due to computer problems affecting several airports nationwide, according to CBS Chicago.

The Federal Aviation Administration said there was a “ground stop” for American Airlines and its subsidiaries at O’Hare, Dallas/Fort Worth International Airport, and Miami International Airport. The agency said it was not an FAA issue, but an internal problem at American.

American Airlines is trying to resolve the issue.