What to know about the Newark mayor's arrest at an immigration detention center

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.

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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?