Story highlights US Customs computers back online after four-hour outage

"Nationwide system shutdown" due to customs computer glitch

(CNN) A computer outage at US airports Monday evening left thousands of inbound international travelers stuck behind customs screening stations for hours on one of the busiest travel days of the year.

The US Customs and Border Protection processing systems were back online at all airports later in the night, spokesman Daniel Hetlage said -- but not before creating long lines of disgruntled holiday travelers.

The outage lasted from about 5 to 9 p.m. ET, Hetlage said. Airport officials and travelers across the country reported delays ranging from 30 minutes to two hours.

@cnnbrk please let US Customs know the Miami airport could use a little help. Thousands of us waiting in a "line". pic.twitter.com/VGLUOUiaoP — Garret Prather (@garretp) January 3, 2017

CBP officers processed international travelers through "alternative procedures" while the agency scrambled to get systems back online.

"During the technology disruption, CBP had access to national security-related databases and all travelers were screened according to security standards," Hetlage said. "At this time, there is no indication the service disruption was malicious in nature."

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