The American Civil Liberties Union and other civil rights groups sued Customs and Border Protection Wednesday to release records concerning units they say are deployed at airports to “target, detain and interrogate innocent travelers.”

The ACLU filed a lawsuit Wednesday calling for CBP to release records about its Tactical Terrorism Response Teams, which the civil rights group described as “highly secretive units” which operate at airports and U.S. ports of entry to detain, question and deny entry to people “with valid travel documents who present no security risk.”

The lawsuit, filed in the U.S. District Court for the Eastern District of New York, said TTRT officers can target travelers who do not present a security risk “but may hold information or have a connection to individuals of interest to the U.S. government.”

The ACLU was joined by CUNY Law School’s Creating Law Enforcement Accountability and Responsibility project and the American Civil Liberties Union Foundation in the suit.

The lawsuit is asking the court to order CBP to disclose requested records to the civil rights groups.

“The tools, methods, and criteria TTRT officers use to determine which travelers to target for detention, search, questioning and/or denial of entry remain secret, as are any policies and guidelines that govern TTRT activities,” the lawsuit said.

In a statement announcing the lawsuit, the ACLU said the “public has a right to know how these teams operate, how their officers are trained, and whether the guidelines that govern their activities contain civil liberties and privacy safeguards.”

“We also want to know just how many individuals are subject to detention, questioning, and/or denial of entry into the United States by these teams, and the basis for these decisions,” the ACLU added.

The statement said that in November 2018, CBP officers detained Andreas Gal, the former chief technology officer at Mozilla and a current Apple employee, at the San Francisco International Airport upon landing from a business trip to Sweden.

Gal was allegedly not given a reason for being detained, except that his receipt from a Global Entry kiosk was marked “TTRT.”

The officers then allegedly asked Gal, a U.S. citizen, about his activism, according to the ACLU. Gal is “an outspoken proponent of online privacy and has spoken publicly about his opposition to warrantless mass surveillance and views on the current administration’s policies,” the ACLU wrote. The officers also allegedly repeatedly sought to search Gal’s electronic devices, according to the suit.

He was eventually allowed to leave, according to the ACLU.

Abdikadir Mohamed, an immigrant, was allegedly detained at John F. Kennedy International Airport in New York in Dec. 2017, the ACLU wrote. He was approached by CBP officers on his way to board a flight to reunite with his pregnant wife and daughter in Ohio after he had cleared immigration and security screenings, according to the ACLU.

He was allegedly taken to a separate room where he was interrogated for 15 hours before CBP deemed he was “inadmissible” and sought to deport him, the ACLU said. Mohamed fought his deportation and sought asylum in the U.S., which he won after 19 months in detention, according to the ACLU.

“CBP’s treatment of Andreas and Abdi is disturbing, and they are not isolated incidents,” the ACLU wrote. “We now know that the officers that targeted Andreas and Abdi are part of a secretive team CBP has deployed to at least 46 airports and other U.S. ports of entry.”

According to the Department of Homeland Security, more than 1,400 people were denied entry to the U.S. as a result of TTRT efforts and information discovered during secondary inspections during fiscal year 2017.

Kevin McAleenan, the former acting Secretary of Homeland Security and former CBP commissioner, described the role the teams play in an interview last year with the Combating Terrorism Center at West Point.

The teams were “a conscious effort” for officers to use their instincts in “encounters that our officers have with travelers to make decisions based on risk for people that might not be known on a watch list, might not be a known security threat, and they’ve been a tremendous success in identifying previously unknown individuals that present a security risk and in denying entry to folks that were not watch listed prior to their travel.”

CBP used a variety of metrics in determining the success of the teams, such “both hard data on individuals that were not watchlisted that were determined to be security risks during a border interview or inspection and were denied entry” and “watchlist nominations that devolve from a good interview at the border.”

Customs and Border Protection said it was unable to comment on pending litigation.