US Customs and Border Patrol (CBP) systems for processing arriving travelers' passports were reportedly down on Friday afternoon, leading to massive delays at airport arrivals halls throughout the country.

JFK Airport's official Twitter account said that Customs agents were using backup systems to process passengers manually.

CBP tweeted that systems were "coming back online" shortly after 6:30 p.m. ET Friday.

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The systems that the US Customs and Border Patrol uses to check incoming travelers' passports suffered a major outage on Friday afternoon, forcing officials to rely on slower backup systems.

Travelers at airports around the country, including New York's JFK and Washington-Dulles, reported widespread delays in international arrivals halls.

"At Dulles, just announced that the US Customs system is down nationwide," one traveler at Washington Dulles tweeted.

Gordon Loesch, a reporter for Pittsburgh-based WPXI-TV, said that he was in a plane sitting on the tarmac in Chicago, and was not being let off the plane because of the outage. He said that the pilot warned it could be "a couple hours," and that passengers were worrying about missing connections.

"US Customs and Border Protection is experiencing a temporary outage with its processing systems at various air ports of entry and is taking immediate action to address the technology disruption," the agency said in a statement. "CBP officers continue to process international travelers using alternative procedures until systems are back online."

"Travelers at some ports of entry are experiencing longer than usual wait times and CBP officers are working to process travelers as quickly as possible while maintaining the highest levels of security," it added.

Shortly after 6:30 p.m. ET, the agency said that it was still working to get the systems back online.

"The affected systems are coming back online and travelers are being processed. CBP will continue to monitor the incident," the agency tweeted. "There is no indication the disruption was malicious in nature at this time."

Videos and photos from airport arrivals halls showed heavy crowding as passengers from arriving flights waited to be processed.

"Just to let you know Customs is experiencing a system shutdown nationwide," JFK Airport's official account tweeted. "They are processing passengers manually until the system comes back online. Thanks for your patience."

The official Twitter account for various other US international airports similarly wanted passengers of delays.

CBP has gained attention over recent months as employees have been reassigned from customs duties at airports to working on the southern border, causing some reports of short staffing for normal airport CBP operations.

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