A nationwide collapse of the US customs service computer system left thousands of passengers lined up at airports awaiting clearance to officially enter the country, the authorities and US media said.
"Customs and Border Protection has nationwide outage. Expect delays in passenger processing until the system is restored," Fort Lauderdale's airport, a major hub for the United States and Caribbean, said on Twitter.
A Customs and Border Protection department spokesman told NBC News that there had been a disruption at several airports and was "taking immediate action to address the technology disruption."
After a few hours of trouble, the glitch was fixed.
"All airports are back on line after a temporary outage of CPB's processing systems. No indication the disruption was malicious in nature," Customs said on Twitter.
But that was not enough for the thousands of tired and cranky passengers who arrived at US gates but then were lined up, in travel limbo, unable to clear customs.
An official for Miami International Airport told NBC that passengers on "more than 30 international flights were affected" and one traveler told the same affiliate that two people fainted waiting in line.
"People are starting to argue and get frustrated," Cali Rez tweeted in Miami. "Get someone down here to explain things and direct the lines ASAP."
The affected airports are known to include Miami International, Atlanta Hartsfield, Boston Logan and Fort Lauderdale, officials said.