Authorities arrested several people near downtown Los Angeles late Tuesday after a curfew came into effect following intense protests againstimmigration enforcement raidsand theescalation of military presenceacross the nation's second-largest city. Los Angeles Mayor Karen Bassdeclared a partial curfewstarting at 8 p.m. local time Tuesday to 6 a.m. Wednesday. The curfew covers one square mile of downtown Los Angeles and is part of the city's strategy to quell ongoing looting and vandalism linked to the protests. Shortly after 9 p.m. local time on Tuesday, the Los Angeles Police Department announced that multiple groups congregated on 1st Street between Spring and Alameda. "Those groups are being addressed andmass arrests are being initiated," the LAPD said. "Curfew is in effect." The curfew, which Bass expects to last for several days, does not apply to residents who live in the designated area, people experiencing homelessness, credentialed media, or public safety and emergency personnel, according to Los Angeles Police Chief Jim McDonnell. The police chief noted that there has been an escalation of "unlawful and dangerous behavior" since Saturday. In a public address Tuesday night, CaliforniaGov. Gavin Newsom condemnedPresidentDonald Trump's deployment of 4,000 National Guard troops and about 700 Marines, a move that state and local officials have called unnecessary, illegal, and politically motivated. Trump, according to Newsom, was not "protecting our communities, he's traumatizing our communities." Reuters reported that about 2,100 National Guard troops were in the greater Los Angeles area on Tuesday, with more on the way. Meanwhile, hundreds of Marines were in a staging area near the city, awaiting deployment to specific locations, according to Reuters. Though few of those troops were actually on the streets, the U.S. Immigration and Customs Enforcementposted photos on Xshowing Guard troops accompanying ICE officers on an immigration raid. Defense SecretaryPete Hegsethreposted the photos, saying: "This We'll Defend." The Trump administration has vowed to redouble immigration enforcement raids in response to the protests, which have expanded to other U.S. cities, including Chicago, New York, and Atlanta. California sued Trump and the Department of Defense on Monday, seeking to block the deployment of federal troops. Newsom has also accused Trump and Hegseth of trying to use the assets to help ICE conduct raids. A judge has set a hearing for the matter for Thursday. Cost estimate: $3.6 billion.Trump wants 20,000 troops to hunt, transport immigrants. California leaders and the Trump administrationremained in a tense standoffas Newsom accused the president of "pulling a military dragnet all across Los Angeles, well beyond his stated intent to just go after violent and serious criminals." The Democratic governor has said in recent days that Trump acted like a "dictator" by deploying federal troops without his consent, and compared the administration to authoritarian regimes for targeting vulnerable people. Newsom reiterated Tuesday that Trump "chose escalation." Trump's "agents are arresting dishwashers, gardeners, day laborers, and seamstresses. That's just weakness. Weakness masquerading as strength," Newsom said. Trump has called Newsom "grossly incompetent" and suggested the governor should be arrested. The president has also insisted that service members deployed to California are "defending the republic itself" and helping the administration "liberate" the city of Los Angeles. On Tuesday, Trump said from the White House that he planned to respond to any protests, including against his June 14 military parade, with "force." Protests in Los Angeles were relatively peaceful when they began on Friday, but escalated into scenes of chaos, with electric vehicles lit aflame, large clouds of tear gas and clashes between law enforcement and demonstrators. Trump has backed his move to send in troops, calling the protests "violent, insurrectionist mobs" and "lawless riots." But Newsom said it was Trump who "instigated violence." Experts say while there are legal definitions for a riot, the term has become increasingly politicized and encapsulates a wide variety of incidents. In most states including California, the key determinator lies in whether multiple people are involved and whether they are committing acts of violence, Brian Higgins, a professor at John Jay College of Criminal Justice in New York, said. "One person is not a riot and neither is a group that is nonviolent," he said. "They can even be breaking the law, like refusing to disperse. It's when you add in the factor of violence that it becomes a riot." There are some gray areas, he said. Experts also said that while violence is a defining factor in a riot, such violence could be incited by law enforcement.Read more. Contributing: Christopher Cann, USA TODAY; Reuters This article originally appeared on USA TODAY:LA protests live: Police make 'mass arrests' after curfew kicks in