An immigration detention center in New Jersey is at the center of tensions between three congressional Democrats and the Trump administration after  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 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.