U.S. Customs and Border Protection said Friday evening that systems around the country were being restored after an earlier outage prevented U.S. immigration officials from processing thousands of arriving passengers during a busy summer travel day.
It wasn't immediately clear what caused the problem at U.S. Customs and Border Protection, but the agency said it will continue investigating. There was no indication that the system was intentionally derailed, according to a CPB official.
CBP officers used "alternative procedures" to process travelers arriving from abroad, the agency said.
Some travelers posted images on social media of long lines at checkpoints at airports in Washington, D.C., and Houston.
One traveler tweeted that passengers on her flight from London weren't allowed to deplane upon arrival in Boston because of the issue.