(Gray News) - A technology issue forced United Airlines to request a ground stop at several major airports on Wednesday night, the airline said.

The outage began just after 6 p.m. Eastern and was resolved within a few hours, but delays continued through the night.

“Due to a technology issue, we are holding United mainline flights at their departure airports,” a spokesperson for United Airlines said in a shared statement. “Safety is our top priority, and we’ll work with our customers to get them to their destinations.”

Notices from the Federal Aviation Administration stated that the airline requested ground stops at airports that included San Francisco, Chicago and Houston.

CNN reported that about 31% of the carrier’s flights were showing delays as of 9:45 p.m. Eastern, with 1% having been canceled.

According to the Associated Press, United said the impacted system was Unimatic, which houses flight information that other systems use to calculate weight and balance and track flight times.

Transportation Secretary Sean Duffy said in a social media post that the issue was unrelated to the broader air traffic control system.

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