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.

Gen. Eric Smith, the commandant of the Marine Corps, told the Senate Armed Services Committee that the 700 Marines being sent to Los Angeles received crowd control training in Twentynine Palms, California.

Sen. Richard Blumenthal, D-Conn., expressed his doubts about the use of combat-trained units domestically, saying he was "deeply worried" that their deployment increased the risk of lethal force possibly being used.

Smith said he’s not concerned, adding, "I have great faith in my Marines."

Smith said the Marines -- who are equipped with shields and batons -- do not have arrest authority but will be providing support to law enforcement protecting federal property and personnel.

Sen. Elissa Slotkin, D-Mich., asked Smith if he knew how much crowd control training Marines receive. Smith said he didn't have the precise number but said it was "in excess of two hours," calling it "a standard annual training in the use of non-lethal means."

Slotkin noted that the police forces on the street receive 600 hours of crowd control training.

-ABC News’ Luis Martinez