A problem in the computer systems used by United States Customs and Border Protection (CBP) authorities has left thousands stuck in airports and unable to enter the country. Officials from the CBP confirmed to CBS News that the outage was nationwide, after many passengers took to Twitter, expressing their frustration at being stranded and sharing photos of huge lines.

In its statement, the CBP said that the outage in its processing systems was temporary, and that it was taking action to fix it. Until then, officers would “continue to process international travelers using alternative procedures.” Posts on social media indicate that passengers were experiencing severe delays in border control in several large airports, including Atlanta, San Francisco, and Washington’s Dulles. Pictures taken in line show cramped and uncomfortable conditions, with wait times upwards of three hours leading to reports of fights, “breakdowns,” and vomit from passengers.

Please be advised, @CustomsBorder outage is nationwide. They are working to restore. Thanks for your patience. — Miami Int'l Airport (@iflymia) January 2, 2017

Other passengers are reportedly stuck on landed planes, waiting in lengthy queues on the ground before they can reach a gate and disembark safely.

Atlanta’s outage lasted about an hour, according to CBP public affairs official Robert Brisley, but it’s not yet clear when the systems will be back online across the country. Passengers still stuck in line may still have several hours to wait while officials clear the backlog.