NEW YORK (AP) — Passengers in several cities say a massive computer outage has stranded United Airlines passengers at airports across the country.

This is at least the third major computer outage for the Chicago-based airline since June.

Passengers are being told by pilots and airport agents that computers are down and they don't know when the system will come back, passengers told The Associated Press. Some fliers have been waiting nearly 2 hours to depart.

A spokesman for United Continental Holdings Inc. did not immediately respond to a request for comment.