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

The airline’s travel alert page notes that a technology disruption may impact flights to or from 14 airports including Newark, Washington, Los Angeles and Chicago.

An undisclosed “technology issue” delayed more than 1,000 United Airlines flights across the U.S. United Airlines said in a statement Wednesday that flights on major routes were held at their departure airports because of a technology issue.