A reporter with The Associated Press witnessed Lander’s arrest at a federal building in Manhattan. The person Lander was walking out of the courtroom was also arrested.

Lander had spent the morning observing immigration court hearings and told an AP reporter that he was there to “accompany” some immigrants out of the building.

At a press conference following the arrest, Lander’s wife, Meg Barnette, said her husband had tried to link arms with a man following his immigration court hearing when “we were swarmed by a number of federal agents.”

“They said, ‘You’re obstructing,'” Barnette said. “I was shoved out of the way.”

“What I saw was shocking and unacceptable,” she added. “What I saw today was not the rule of law.”

A video of the arrest, captured by an AP reporter, shows an agent telling Lander, “You’re obstructing.”

In the moments before Lander was handcuffed, agents could be seen trying to physically separate Lander from the man they had come to detain. Lander briefly struggled to stay close to the detainee before he was pulled away.

“I’m not obstructing, I’m standing right here in the hallway,” Lander said as he was being handcuffed.

“You don’t have the authority to arrest U.S. citizens asking for a judicial warrant,” Lander said as he was led away down a hallway and into an elevator.

One of the officers who led Lander away wore a tactical vest labeled “federal agent.” Others were in plainclothes, with surgical masks over their faces.

The episode occurred as federal immigration officials are conducting large-scale arrests outside immigration courtrooms across the country.

In many cases, immigrants are arrested after a judge grants a government request to dismiss their case, making them eligible for expedited removal.

“They remove any opportunity for due process,” Lander had told reporters earlier in the day after witnessing another person’s hearing.

Lander’s detainment comes a little more than a month after Newark, New Jersey, Mayor Ras Baraka was arrested on a trespassing charge outside a federal immigration detention center in his city.

The charge was later dropped by interim U.S. Attorney for New Jersey Alina Habba, and Baraka’s fellow Democrat, Rep. LaMonica McIver, was charged with assaulting and impeding federal agents stemming from her role at the same visit as the mayor. A federal indictment charges she grabbed, pushed and blocked officers from arresting the mayor. She’s denied the charges and said she plans to fight them. Baraka filed a federal lawsuit against Habba alleging false arrest and malicious prosecution.

A spokesperson for the FBI deferred comment to the Department of Homeland Security, which did not respond to an emailed inquiry.

Lander is a candidate in the city’s Democratic mayoral primary. Early voting in the contest is underway and the election is next week.

In a statement, Lander’s campaign said, “While escorting a defendant out of immigration court at 26 Federal Plaza, Brad was taken by masked agents and detained by ICE.”