Customs and Border Protection agents met a domestic flight at John F. Kennedy Airport on Wednesday night and checked the IDs of every passenger on board, according to one traveler who documented the scene.

The incident, which took place on Delta Flight 1583 from San Francisco, was atypical for both domestic flights—on which no identification is needed to exit the airport—and international flights, where identification is checked during a customs screening after deplaning.

A spokesman for CBP told Gothamist that such checks are "not a new policy" and that it is "not unusual for us to assist our fellow law-enforcement agencies."

CBP declined to comment on which agency it was working with on Wednesday, but said collaborative agencies might include Homeland Security, or any local or national law enforcement agency. The spokesman also said that CBP was seeking an individual, who, it turned out, was not on the flight. [CBP has since stated that the agents were assisting ICE in seeking a person with a removal order. See below for update.]

Matt O'Rouke of Manhattan, 41, photographed two agents standing on either side of the plane entrance shortly after 8:30 p.m. on Wednesday, checking identification. He described the experience to Gothamist.

"When we were getting out there were two customs agents," he recalled. "I don't think they had a clipboard or a list. I think they were just looking at everybody's ID. They did it really carefully. You could tell they weren't just looking for a name. They read my entire ID and looked at me the entire time. I was probably the tenth person off the plane, and they did the same for everyone in front of me."

When the plane landed, O'Rouke said, a flight attendant announced over the intercom that all passengers should take out their identification.

"The head flight attendant came on and said, 'Please have your papers ready' three or four times," O'Rouke recalled. Passengers then asked why papers were necessary on a domestic flight. "Someone corrected her and she said, 'Oh I mean photo IDs,'" he added. "To which people were kind of weirded out."

"I flew almost 200,000 miles last year," O'Rouke said. "I've never had my ID checked getting off a domestic flight."

Earlier this week, the Department of Homeland Security issued guidelines for CBP and Immigration and Customs Enforcement (ICE) to implement President Donald Trump's immigration policy. The guidelines basically eliminate the concept of deportation priorities, leaving it up to ICE offices to decide who among the millions in the United States without a visa to go after.

Jordan Wells, a staff attorney with the New York Civil Liberties Union, told Gothamist that this sort of behavior is not necessarily indicative of immigration enforcement. Border agents have been known to check IDs if they have reason to believe someone on the flight is on the FBI's wanted list, for example.

But CBP's comment on the matter, he said, was not specific enough to determine whether Wednesday's searches were indeed typical, as the agency maintains.

"CBP does not have carte blanche to detain people for questioning without suspicion just because they step off of a domestic flight within 100 miles of a border," he said. "It is not an always-and-everywhere police force, and any attempt to expand its operations beyond its authority would raise serious concerns."

Ward Oliver, supervising attorney for the Immigration Law Unit at the Legal Aid Society, stressed that the incident seemed highly unusual, and consistent with the regime laid out in the new DHS memos.

"I can't say that I've ever heard of this happening at Kennedy Airport before," he said. "To me it seems pretty clear to me what they are doing, in light of the order."

He added that there has historically been legal precedent for agents to question individuals at checkpoints within 100 miles of the US border. JFK is within that 100 mile zone, "But it seems like an abuse [of that right] of it's in the airport on a domestic flight."

Port Authority spokesman Scott Ladd deferred comment to Delta and CBP, saying, "This isn't our area or jurisdiction."

Delta spokeswoman Elizabeth Wolf did not immediately comment on the incident.

[Update 1:30 p.m.] This piece has been updated with comment from CBP.

[Update 2:45 p.m.]: According to a CBP spokesman, the agency "was contacted by U.S. Immigration and Customs Enforcement (ICE) yesterday, February 22, 2017, to assist in locating an individual possibly aboard Delta flight 1583 from San Francisco International Airport to JFK. This individual was ordered removed by an immigration judge."

"To assist our law enforcement partners, two CBP officers requested identification from those on the flight in order to help identify the individual," he added. "The individual was determined not to be on the flight."

[Update 4:45 p.m.]: According to CBP, the person agents sought had been issued an order of removal based on convictions for domestic assault, driving while impaired, and violation of an order of protection.