The New York Police Department has activated its Joint Operations Center in coordination with FBI, state, local and federal partners ahead of what is expected to be widespread protests Saturday across the city.

Some 34,000 members of the NYPD will be on the streets of New York City over the next 24 hours.

"You do not have a right to engage in violence and lawlessness," Mayor Eric Adams said in a news conference yesterday ahead of the planned protests.

United States Army North confirmed to ABC News that Marines at the Wilshire Federal Building have made the first temporary detention among the troops sent to Los Angeles on Friday.

In an interview earlier in the week, Maj. Gen. Scott Sherman -- the commander of Joint Task Force 51 -- said, "We're there to protect their federal officers, their federal personnel.”

If those personnel are assaulted, Sherman said, "Soldiers or Marines are allowed to take that person, detain them in place, wait for the federal law enforcement officer to come and arrest that individual."

It was not immediately clear what led to the detainment on Friday.

-ABC News' Luis Martinez

About 200 Marines are taking over responsibility for protecting the Wilshire Federal Building in Los Angeles, Maj. Gen. Scott Sherman told reporters Friday.

The addition of those troops will allow more National Guardsmen to be trained to accompany federal personnel during Immigration and Customs Enforcement raids, according to Sherman.

“The soldiers that were performing those duties will then transition to providing protection to federal law enforcement officers as they conduct their law enforcement function,” Sherman said. “I would like to emphasize that the soldiers will not participate in law enforcement activities. Rather, they'll be focused on protecting federal law enforcement personnel."

Sherman serves as the commander of Joint Task Force 51, the command headquarters for the 4,000 federalized National Guardsmen and 700 Marines assigned to protect federal personnel and property in Los Angeles.

In an interview with ABC and the Associated Press earlier this week, Sherman said, as of then, about 500 of the 4,000 National Guardsmen assigned to the LA area had been specifically trained to work with ICE teams.

-ABC News' Luis Martinez

Marines are now on duty in Los Angeles for the first time. Some were spotted guarding the Wilshire Federal Building on Friday.

The hearing for California Governor Gavin Newsom and Attorney General Rob Bonta's emergency request to block President Trump and the Department of Defense from “expanding the current mission of federalized Cal Guard personnel and Marines” is set to take place on Thursday.

“This mission orders soldiers to engage in unlawful civilian law enforcement activities in communities across the region, beyond just guarding federal buildings,” the statement said. “The federal government is now turning the military against American citizens, sending trained warfighters onto the streets is unprecedented and threatens the very core of our democracy. Donald Trump is behaving like a tyrant, not a President. We ask the court to immediately block these unlawful actions.”

The request was filed as part of Newsom’s lawsuit against Trump, Defense Secretary Pete Hegseth and the Department of Defense.

“The president’s actions have not only caused widespread panic and chaos, but have unnecessarily created an additional diversion of resources as the state tries to calm a community terrorized by this reckless federal action,” Newsom said.