A spokesperson for the airport told CP24 that the issue forced US customs officials to process travellers manually, resulting in significant delays.
The MIA computers went down at around 4:30 p.m. Friday, said airport spokesperson Greg Chin. About 24,000 worldwide travelers pass through DFW Airport each day.
The agency later tweeted: "The affected systems are coming back online and travellers are being processed".
John F. Kennedy International Airport in NY tweeted that passengers were being processed manually.
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United States media say officers are manually processing passengers.
It's unclear so far whether Friday afternoon's troubles are connected with the biometric program or another aspect of Customs systems.
Some have reported border patrol officers waiting for the systems to come back online, rather than process people by hand.
Earlier, CBP said officers were processing global travelers using alternative procedures, which caused "longer than usual wait times".
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The agency said it was using "alternative procedures" to process worldwide travellers during the outage.
"Easily 5,000+ passengers in line at Dulles", she estimated.
This is not the first time the system has faced problems.
CBP added that they were processing passengers manually. "The agents are processing people manually".
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Many travelers took to social media to share videos of long lines at airports across the country.