(CNN) — United Airline flights were grounded Wednesday morning due to a problem with the airline's computer system, the FAA reported.
The extent of the problem and whether it affected flights outside the United States was not immediately known.
United spokesmen were not available for comment, but the airline's twitter account responded to customer complaints, saying "We are working on getting you to your destination as quickly as possible."
The systemwide computer problem was forcing United to hand write tickets for passengers at multiple airports.
The problem started shortly before 9 a.m. ET, and affected both United and the feeder airlines that fly under names such as United Express. By 9:20 a.m., the feeder airlines were released from the ground stop, according to the FAA, but the United flights were still grounded.