ST. PAUL, Minn. (AP) — Federal prosecutors have charged 15 people with impeding the Trump administration’s immigration crackdown in Minnesota earlier this year, accusing them of coordinating efforts to block deportations as part of a conspiracy against the U.S. government.

During a news conference Tuesday, Minnesota U.S. Attorney Daniel N. Rosen said the monthslong investigation focused on two activist groups whose members and associates “violently opposed the enforcement of federal law."

He characterized the groups as “antifa,” an umbrella term for a diffuse movement of militant left-wing activists.

Information for the defendants' attorneys was not immediately available.

The indictment comes as the Trump administration continues to target protesters associated with “antifa,” which he has labeled a domestic terrorist group.

In March, eight people accused of having ties to antifa were convicted on terrorism charges in a Texas shooting, a first of its kind case that raised concerns among some civil liberties groups.

The 15 people charged Tuesday were part of “Direct Action Minnesota,” a left-wing coalition of protest groups that trains its members in the “surveillance, operational planning and rapid mobilization against law enforcement,” Rosen said.

Their alleged actions include “stalking” U.S. Immigrations and Customs Enforcement agents, throwing blocks of ice at their vehicles, setting up blockades around federal buildings and passing out shields to demonstrators. Rosen declined to say whether any federal agents were injured as a result.

“Whether or not they actually, at the end of the day, cause bodily harm is not the measure of whether or not they committed a serious federal crime,” he told reporters.

Asked about the Justice Department's definition of "antifa,” Rosen said the question was “beyond the scope” of the indictment, but noted that several defendants had self-identified with the label.

On Tuesday afternoon, dozens of protesters gathered outside a federal courthouse in St. Paul, where most of the defendants were set to make an initial appearance. As some in the crowd attempted to block a courthouse door, federal officers in tactical gear deployed pepper spray at the group.

Each of the defendants was charged with conspiracy to impede or injury a federal officer, which carries a maximum sentence of six years in prison. Three others faced additional charges, including interstate stalking, assault on a federal officer and destruction government property.

One of the defendants, Kyle Wagner, 37, was previously arrested on charges that he made online threats against ICE officers and their supporters. An attorney listed for Wagner in that case did not respond to a message seeking comment.

The alleged conspiracy began in January, shortly after the Trump administration launched its sweeping immigration crackdown, dubbed Operation Metro Surge, in response to reports of fraud within Minnesota's Somali community.

The operation — described by the Department of Homeland Security as the largest in its history — brought thousands of federal agents, who often wore masks and traveled in unmarked SUVs, into the Twin Cities and surrounding areas.

Their arrival drew fierce protests from Minnesota residents, who quickly set up a sprawling network of anonymous Signal chats to track the movement of ICE agents. Protesters then used whistles and car horns to draw attention to detentions as they were happening.

Despite the intense pushback, federal prosecutors said the operation resulted in more than 4,000 arrests.

The administration framed the operation as a response to a burgeoning federal investigation into billions of dollars in fraud within Minnesota programs tied to Medicaid. Dozens of Somali immigrants have been convicted or implicated. Trump has called the state’s Somali population “garbage.”

Gov. Tim Walz and Minneapolis Mayor Jacob Frey sought to defend the Somali population and condemned Trump for sending federal officers where they weren’t needed or wanted.

In the months since, federal authorities have sought to prosecute protesters they blame for violence, while state and local Minnesota officials have pursued assault charges against at least two federal officers. The agents who fatally shot two protesters, Alex Pretti and Renee Good, have not been charged.

Walz and Ellison did not immediately respond to email messages Tuesday seeking comment on the federal indictment.