California National Guard troops arrived in Los Angeles on Sunday to quell demonstrations over President Donald Trump's immigration enforcement, as the state's Democratic governor called their deployment unlawful.

The National Guard began deploying as demonstrations over federal immigration raids continued for a third day in Los Angeles, culminating in confrontations between protesters and police.

Los Angeles police declared one rally near City Hall to be an "unlawful assembly," alleging that some protesters threw concrete, bottles and other objects at police. "Arrests are being initiated," the department wrote in a post on social media.

Demonstrators shouted "shame on you" at police and some appeared to throw objects, according to video. A group of protesters blocked the 101 Freeway, a major thoroughfare in downtown Los Angeles.

California Governor Gavin Newsom said he requested the Trump administration withdraw its order to deploy 2,000 National Guard troops in Los Angeles County, calling it unlawful.

Newsom accused Trump of trying to manufacture a crisis and violating California's state sovereignty. "These are the acts of a dictator, not a President," he wrote in a post on X.

The White House disputed Newsom's characterization, saying in a statement that "everyone saw the chaos, violence and lawlessness."

Earlier, about a dozen National Guard members, along with Department of Homeland Security personnel, pushed back a group of demonstrators that amassed outside a federal building in downtown Los Angeles, video showed.

Trump in a social media post on Sunday, called the demonstrators "violent, insurrectionist mobs" and said he was directing his cabinet officers "to take all such action necessary" to stop what he called "riots."

Speaking to reporters in New Jersey, he threatened violence against demonstrators who spit on police or National Guard troops, saying "they spit, we hit." He did not cite any specific incidents.

"If we see danger to our country and to our citizens, it will be very, very strong in terms of law and order," Trump said.

National Guard troops were also seen in Paramount, in southeast Los Angeles, near the Home Depot, the site of altercations between protesters and police on Saturday.

Law enforcement faced off with a few hundred protesters in Paramount and 100 in downtown Los Angeles on Saturday, with federal officers firing gas canisters in efforts to disperse crowds, according to Reuters witnesses.

Authorities in Los Angeles arrested about 30 people on Saturday, including three on suspicion of assaulting an officer. The Los Angeles County Sheriff's Office said three deputies sustained minor injuries.

The FBI offered a $50,000 reward for information on a suspect accused of throwing rocks at police vehicles in Paramount, injuring a federal officer.

Despite Trump's rhetoric about the demonstrations, he has not invoked the Insurrection Act, an 1807 law that empowers a president to deploy the U.S. military to suppress events like civil disorder. Asked on Sunday whether he was considering invoking the law, he replied "it depends on whether or not there's an insurrection."

The protests pit Democratic-run Los Angeles, where census data suggests a significant part of the population is Hispanic and foreign-born, against Trump's Republican White House, which has made immigration enforcement measures a hallmark of his second term.

Defense Secretary Pete Hegseth has warned that the Pentagon was prepared to mobilize active-duty troops "if violence continues" in Los Angeles, saying the Marines at nearby Camp Pendleton were "on high alert."

Los Angeles Mayor Karen Bass said her city’s law enforcement would have been able to handle the protesters, and blamed the Trump administration for inciting tensions by sending in the National Guard.

"It’s a feeling here of intentional chaos in a situation that had not broken out to violence short of a few people," Bass, a Democrat, said on CNN.

Democratic Congresswoman Nanette Barragan, whose California district includes Paramount, also blamed the Trump administration.

"It's only going to make things worse in a situation where people are already angry over immigration enforcement," Barragan told CNN's "State of the Union."

Vanessa Cárdenas, the head of the immigration advocacy group America's Voice, accused the Trump administration of "trumping up an excuse to abuse power, and deliberately stoke and force confrontations around immigration."

Homeland Security Secretary Kristi Noem told CBS' "Face the Nation" on Sunday that the National Guard would provide safety around buildings to people engaged in peaceful protest and to law enforcement.

ICE operations in Los Angeles on Friday arrested at least 44 people on alleged immigration violations. The Department of Homeland Security on Sunday shared information about what it said were the criminal records of some of those arrested.

Trump has pledged to deport record numbers of people in the country illegally and lock down the U.S.-Mexico border, setting a goal for ICE to arrest at least 3,000 migrants per day.

But the sweeping enforcement measures have also included people legally residing in the country, some with permanent residence, and has led to legal challenges.

Mexican President Claudia Sheinbaum on Sunday criticized the U.S. government over the immigration raids and deployment of the National Guard.

"We do not agree with this way of addressing the immigration issue," Sheinbaum, who has sought to cultivate a positive relationship with Trump, said at a public event. "The phenomenon will not be addressed with raids or violence. It will be by sitting down and working on comprehensive reform."

Trump's justification for the National Guard deployment cited a provision of Title 10 of the U.S. Code on the Armed Forces. However, Title 10 also says the "orders for these purposes shall be issued through the governors of the States."

It was not immediately clear if the president had the legal authority to deploy the National Guard troops without Newsom's order.

Title 10 allows for National Guard deployment by the federal government if there is "a rebellion or danger of a rebellion against the authority of the Government of the United States." Those troops are only allowed to engage in limited activities and cannot undertake ordinary law enforcement activities.

Trump's memo says the troops will "temporarily protect ICE and other United States Government personnel who are performing Federal functions, including the enforcement of Federal law, and to protect Federal property, at locations where protests against these functions are occurring or are likely to occur."