An undisclosed “technology issue” has grounded United Airlines flights across the U.S. United Airlines said in a statement Wednesday that flights on major routes were being held at their departure airports because of a technology issue.

United Airlinesbriefly suspended flight departures nationwide because of a technology issue and expected further flight delays throughout the night.

United Airlines has grounded flights nationwide on Wednesday night due to an issue with its weight and balance computer system, according to the airline.