Concord Coach Lines, a popular bus service that serves much of northern New England, has apologized after video surfaced of an employee falsely telling passengers in Bangor that they needed to be U.S. citizens to ride.

The unidentified employee was captured in video taken by passenger Alec Larson on May 28, according to News Center Maine WCSH/WLBZ. It was taken while U.S. Customs and Border Protection agents were at the bus station asking would-be riders about their citizenship.

When an agent approached Larson, he responded, “I’m not answering that question, sir,” and the man moved on.

Others, though, wondered aloud whether citizenship was required to ride. One asked the bus terminal employee, who replied, “Yes.”

“This terminal employee was caught off-guard with a question that he was unprepared to answer and made a mistake that we share,” Concord Coach Lines said in a statement released Friday. “On June 1, we communicated with our staff, reiterating and clarifying that we allow anyone and everyone to ride our bus regardless of citizenship.”

The experience in Bangor was the latest example of border patrol checks at bus stations in Maine in the past year as the Trump administration has cracked down on immigration.

Customs and Border Protection agents have the authority to conduct citizenship checks without a warrant within 100 miles of the nation’s land and coastal borders. That includes the entire state of Maine.

Ten other states – Connecticut, Delaware, Florida, Hawaii, Massachusetts, New Hampshire, New Jersey, New York, Rhode Island and Vermont – lie entirely or almost entirely in that 100-mile zone.

A spokeswoman for Customs and Border Protection said the department has increased its transportation checks around the country “to reinforce CBP’s world-class approach to border security.” She said transportation centers are often used by “alien-smuggling and drug-trafficking organizations to move people, narcotics and contraband to interior destinations throughout the country.”

The American Civil Liberties Union of both Maine and New Hampshire urged Concord Coach Lines in April to create a formal policy not to allow Customs and Border Patrol agents on buses without a warrant, except at the border. The civil rights organization sent a similar letter to Greyhound, another major bus carrier that operates in Maine.

In its statement, Concord Coach Lines said it has no agreement with the federal agency. It said agents often show up “without any forewarning,” and that employees have “very little interaction,” with them.

While bus checks appear to be happening more frequently, no publicly available data has been released to support or refute that.

Last month, the ACLU of Maine sued two federal agencies over an unfulfilled public records request related to citizenship checks at major transportation hubs.