As Los Angeles enters a second night under curfew, the city and the nation watch closely to see if calm will hold or protests escalate further amid one of the most intense immigration enforcement efforts in recent US history.

Downtown Los Angeles remained tense on Wednesday as nearly 400 arrests have been made during days of unrest sparked by immigration enforcement operations.

Speaking alongside 30 regional mayors at a news conference Wednesday, Los Angeles Mayor Karen Bass directly blamed the protests on President Donald Trump's immigration raids, which she said had "provoked" residents by causing "fear" and "panic".

"A week ago, everything was peaceful," Bass said. "Things began to be difficult on Friday when raids took place."

She suggested Los Angeles was caught in "part of a national experiment to determine how far the federal government can go in taking over power from a local government, from a local jurisdiction". Bass has previously called on the administration to end the raids.

Bass imposed an 8 pm-to-6 am curfew Tuesday within a roughly one-square-mile area of downtown after escalating vandalism and looting.

"I wanted to stop the vandalism, to stop the looting," she told reporters during a news conference Tuesday morning. "The city had reached a tipping point."

After the curfew took effect at 8 pm local time on Tuesday, police from the Los Angeles Police Department (LAPD) moved through downtown, firing rubber bullets to disperse crowds.

"The curfew is a necessary measure to protect lives and safeguard property following several consecutive days of growing unrest throughout the city," LAPD Chief Jim McDonnell said.

The curfew, which covers roughly 1 square mile in the heart of the nation's second-largest city, was enacted amid mounting tensions over federal immigration enforcement.

"Some of the imagery of the protests and the violence gives the appearance as though this is a citywide crisis, and it is not," McDonnell added.

At the White House on Wednesday, US Attorney General Pam Bondi told reporters that the curfew "helped a bit" in reducing unrest.

Overnight into Wednesday, the LAPD conducted "mass arrests" following the fifth day of protests. According to a series of police statements, those detained included 203 people arrested for failure to disperse, 17 for curfew violations, three for possession of a firearm, and one for assault with a deadly weapon on a police officer. Two officers were injured during the clashes.

The total number of arrests since protests began has approached 400, including 330 undocumented migrants and 157 individuals charged with assault, obstruction and other offenses. Federal prosecutors have charged two men with throwing Molotov cocktails at police officers in separate incidents.

To assist in controlling the unrest and protecting federal facilities and personnel, the Trump administration has deployed over 4,000 National Guard troops and 700 Marines throughout the Los Angeles region.

Major General Scott Sherman, commander of Task Force 51 overseeing the deployment, told The Associated Press that about 500 Guard members have received specialized training to support immigration enforcement.

Guard troops have temporarily detained civilians during protests but do not participate in arrests, immediately transferring custody to law enforcement.

"We are expecting a ramp up," Sherman warned, signaling concern over potential increases in protest activity as federal immigration operations continue.

The military presence and federal actions have provoked strong backlash and sparked legal challenges. In a televised address Tuesday evening, California Governor Gavin Newsom said that Trump's decision to deploy military forces to respond to immigration protests in Los Angeles has brought the country to the brink of authoritarianism.

Calling it a "perilous moment" for democracy and the rule of law, Newsom urged Americans to resist what he described as a dangerous overreach of federal power.

"California may be first, but it clearly won't end here. Other states are next. Democracy is next," he said. "Democracy is under assault right before our eyes — the moment we've feared has arrived."

However, the Justice Department on Wednesday dismissed Newsom's request to limit Trump's National Guard deployment in Los Angeles as a "crass political stunt that endangers American lives", according to a new federal court filing.

Trump posted on his Truth Social on Wednesday morning that, "If our troops didn't go into Los Angeles, it would be burning to the ground right now."

Immigrant rights advocates sharply criticized the raids and militarized response. "Our community is under attack and is being terrorized. These are workers, these are fathers, these are mothers, and this has to stop," said Angelica Salas, executive director of the Coalition for Humane Immigrant Rights.

She condemned the federal tactics, which include warrantless operations in homes, businesses and workplaces, as fueling widespread fear.

Agencies contributed to the story.

renali@chinadailyusa.com