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.

Defense Secretary Pete Hegseth told lawmakers "it's not my lane" to say whether or not the Department of Defense would comply if a judge ordered a withdrawal of National Guard and Marines from LA.

"It's not your legal view that makes the decision in America. It's the federal judiciary," said Rep. Ro Khanna, D-Calif. "If the federal court ... judge has an order [that] is a preliminary injunction, will you agree to abide by the federal courts?"

"What I will tell you is my job right now is to ensure the troops that we have in Los Angeles are capable of supporting law enforcement in there," Hegseth replied. "This is not my lane. But we also recognize that the way in which the judiciary has expanded its powers.”

Rep. Salud Carbajal, D-Calif., a former Marine, ripped Hegseth over the Marine deployment in LA and Hegseth's refusal to say political allegiance should not be required for military service.

"You're not worthy of my attention or my questions. You're an embarrassment to this country. You're unfit to lead," Carbajal said. “And there's been bipartisan members of Congress that have called for your resignation. You should just get the hell out and let somebody competently lead this department.”

-ABC News’ Chris Boccia