NEWARK, N.J. – An immigration detention center in New Jersey is at the center of tensions between three congressional Democrats and the Trump administration after the arrest of Newark’s mayor set off a scrum outside the complex.

Federal prosecutors charged Newark Mayor Ras Baraka with trespassing after agents arrested him outside the fence of the Delaney Hall detention center on Friday. The interim U.S. attorney for New Jersey says Baraka, a Democrat who is running for governor, ignored warnings to leave while he was there with three members of New Jersey’s congressional delegation at the 1,000-bed Immigration and Customs Enforcement facility.

The arrest escalated into a brief but tense confrontation in the parking lot that included the members of Congress and federal agents, some of whom wore masks. Department of Homeland spokeswoman Tricia McLaughlin has accused Baraka of playing “political games” and said over the weekend that an investigation is ongoing and that more actions could be taken.

The three members of Congress — Reps. LaMonica McIver, Bonnie Watson Coleman and Robert Menendez Jr. — have accused federal agents of escalating the situation by arresting the mayor.

Here’s what to know:

Why were members of Congress at the facility?

The representatives have said they went to the facility to inspect it as a matter of congressional oversight.

“We were able to get in, speak to detainees, check out the facilities, and make sure everything was OK there,” Rep. Watson Coleman told CNN in an interview Sunday that also included her two New Jersey colleagues. “We were there almost two hours before the confrontation took place, but ICE kept giving us the run-around and kept saying that they needed to talk to someone else.”

Department of Homeland Security officials have said that lawmakers had not asked for a tour of Delaney Hall and that the agency would have facilitated one. Watson Coleman spokesperson Ned Cooper has said the three lawmakers went there unannounced because they planned to inspect it, not take a scheduled tour.

Why was the mayor of Newark arrested?

Alina Habba, interim U.S. attorney for New Jersey, said on the social media platform X that Baraka was arrested after the mayor allegedly trespassed at the detention facility. She accused him of ignoring warnings to leave the facility, which he has denied.

Baraka was arrested, booked and released the same day. He said he has a court appearance scheduled for Thursday.

In video reviewed by The Associated Press, a federal official in a jacket with the logo of the Homeland Security Investigations can be heard telling Baraka he could not enter the facility because “you are not a congress member.” He was arrested after returning to the public side of the gate at the facility where protesters were gathered, video shows.

Baraka, who is running to succeed term-limited Gov. Phil Murphy, has argued against the opening of the center, citing building permit issues. The facility, located along an industrial stretch of Newark Bay, opened on May 1.

What is this Newark detention center, and why has it been in the news?

Delaney Hall is a two-story building next to a county prison in Newark Bay that operated as a halfway house in previous years. In February, Immigration and Customs Enforcement announced that it and the GEO Group reached a $1 billion, 15-year deal for the detention center. The deal is significant for its size and duration, and GEO officials cited it in messages to investors as a big revenue generator

The 1,000-bed capacity is also significant in advancing President Donald Trump’s goals of expanding detention capacity in the U.S. beyond the previous 41,000 beds, in New Jersey, Michigan, and other states to 100,000 beds.

Democrats, including Baraka, have opposed the opening of the facility. As mayor, Baraka sued to block the opening of the detention center, saying it hadn’t completed all building requirements.

DHS has said that the facility has the proper permits and completed the proper inspections.