(AP) — New York City comptroller and Democratic mayoral candidate Brad Lander was arrested by federal agents at an immigration court Tuesday as he was trying to accompany a person out of a courtroom.

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.

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.

Emailed inquiries to the FBI and U.S. Immigration and Customs Enforcement were not immediately returned.

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