LOS ANGELES (AP) – Police have arrested more than 2,000 people during pro-Palestinian protests at college campuses across the United States in recent weeks, according to an Associated Press tally Thursday.

Demonstrations—and arrests—have occurred in almost every corner of the nation. But in the last 24 hours, they have drawn the most attention at the University of California, Los Angeles, where chaotic scenes played out early Thursday when officers in riot gear surged against a crowd of demonstrators.

Hundreds of protesters at UCLA defied orders to leave, some forming human chains as police fired flash-bangs to break up the crowds.

At least 200 people were arrested, said Sergeant Alejandro Rubio of the California Highway Patrol, citing data from the Los Angeles County Sheriff’s Department. Mr. Rubio said they were being booked at the county jails complex near downtown Los Angeles. UCLA police will determine what charges to bring.

Later Thursday morning, workers removed barricades and dismantled the protesters’ fortified encampment. Bulldozers scooped up bags of trash and tents. Some buildings were covered in graffiti.

Tent encampments of protesters calling on universities to stop doing business with Israel or companies they say support the war in Gaza have spread across campuses nationwide in a student movement unlike any other this century.

The demonstrations began at Columbia University on April 17, with students calling for an end to the Israel-Hamas war, which has killed more than 34,000 Palestinians in the Gaza Strip, according to the Health Ministry there. Israel launched its offensive in Gaza after Hamas militants killed about 1,200 people, mostly civilians, and took roughly 250 hostages in an attack on southern Israel on October 7.

UCLA Chancellor Gene Block said in statement Thursday that the encampment had become “a focal point for serious violence as well as a huge disruption.” He said days of clashes between demonstrators and counter-demonstrators endangered people on campus, students were unable to get to class, buildings had to be closed and classes were canceled.

About 300 protesters voluntarily left after warnings, while more than 200 resisted orders to disperse and were arrested, Mr. Block said.

“The past week has been among the most painful periods our UCLA community has ever experienced,” he said. “It has fractured our sense of togetherness and frayed our bonds of trust, and will surely leave a scar on the campus.”

California Highway Patrol officers poured into the UCLA campus by the hundreds early Thursday. Wearing face shields and protective vests, they held their batons out to separate themselves from demonstrators, who wore helmets and gas masks and chanted: “You want peace. We want justice.”

For hours, officers warned over loud speakers that there would be arrests if the crowd did not disperse. Protesters and police shoved and scuffled. Police helicopters hovered and the sound of flash-bangs pierced the air. Police pulled off protesters’ helmets and goggles as they made arrests.

Police methodically tore apart the encampment’s barricade of plywood, pallets, metal fences and dumpsters, then pulled down dozens of canopies and tents. The number of protesters diminished through the morning, some leaving voluntarily with their hands up and others detained by police.

The law enforcement presence and continued warnings contrasted with the scene Tuesday night, when counterdemonstrators attacked the pro-Palestinian encampment, throwing traffic cones, releasing pepper spray and tearing down barriers. Fighting between the two sides continued for hours before police stepped in. No one was arrested, but at least 15 protesters were injured. Authorities’ tepid response drew criticism from political leaders, Muslim students and advocacy groups.

By Wednesday afternoon, a small city sprang up inside the reenforced encampment, with hundreds of people and tents on the quad. Demonstrators rebuilt the makeshift barriers around their tents while state and campus police watched.

Some protesters said Muslim prayers as the sun set, while others chanted “we’re not leaving” or passed out goggles and surgical masks. They wore helmets and headscarves, and discussed the best ways to handle pepper spray or tear gas.

The crowd grew as the night wore on and as more officers poured onto campus.

Ariel Dardashti, a graduating UCLA senior studying global studies and sociology, said no student should feel unsafe on campus.

“It should not get to the point where students are being arrested,” Dardashti said on campus Thursday.

Dardashti said he can relate to the trauma suffered by Palestinians.

“When my dad was fleeing Iran, he prayed that his children wouldn’t have to face anti-Semitism,” Dardashti said. “We’re afraid of having to flee again in the same way our parents did.”

California Gov. Gavin Newsom denounced the delayed law enforcement response on Tuesday and Mr. Block promised to investigate. The head of the University of California system, Michael Drake, ordered an “independent review of the university’s planning, its actions and the response by law enforcement.”

“The community needs to feel the police are protecting them, not enabling others to harm them,” Rebecca Husaini, chief of staff for the Muslim Public Affairs Council, said during a news conference Wednesday.

Iranian state television carried live images of the police action at UCLA, as did Qatar’s pan-Arab Al Jazeera satellite network. Live images of Los Angeles also played across Israeli television networks.

Israel has branded the protests antisemitic, while Israel’s critics say it uses those allegations to silence opposition. Although some protesters have been caught on camera making antisemitic remarks or violent threats, protest organizers—some of whom are Jewish—call it a peaceful movement to defend Palestinian rights and protest the war.

President Joe Biden on Thursday defended the students’ right to peaceful protest but decried the disorder of recent days.

California Republican leaders blasted university administrations for failing to protect Jewish students and allowing protests to escalate into “lawlessness and violence.” They called for the firing of leaders at UCLA and Cal Poly Humboldt and pushed for a proposal that would cut pay for university administrators.

“We’ve got a whole lot of people in these universities drawing six figure salaries and they stood by and did nothing,” Assembly Republican Leader James Gallagher told reporters. “There does need to be accountability.”

Meanwhile, protest encampments at schools across the U.S., were cleared by police—resulting in more arrests—or closed up voluntarily. In New York, those included the City College of New York, Fordham University, Stony Brook University and the University of Buffalo. Others nationwide included the University of New Hampshire in Durham, Northern Arizona University in Flagstaff, and Tulane University in New Orleans.

A college professor from Illinois said he suffered multiple broken ribs and a broken hand during a pro-Palestine protest on Saturday at Washington University in St. Louis, Missouri.

Bystander video shows the arrest of Steve Tamari, a history professor at Southern Illinois University Edwardsville. He seems to be moving in to take video or photos of protesters being detained when multiple officers roughly take him down.

In a post on the social platform X, Sandra Tamari said her husband needed surgery on his hand and has nine broken ribs.

Tamari said in a statement Thursday that it was “a small price to pay for Israel’s ongoing genocide in Gaza.” Campus police referred questions to the university’s communications department, which did not respond to a request for comment.

Elsewhere, University of Minnesota officials reached agreement with protesters not to disrupt commencements. Similar agreements have been made at Northwestern University in suburban Chicago and Brown University in Rhode Island.

Meanwhile, a professors group at Columbia University condemned school leadership on Thursday for asking police to remove protesters in what the group called a “horrific police attack on our students.” Officers burst into a building Tuesday, breaking up a demonstration that had paralyzed the school.

U.S. college campuses have become a flashpoint, with school leaders facing intense scrutiny over their handling of allegations of antisemitism and the right to free speech. The presidents of Harvard and the University of Pennsylvania resigned following questions at a congressional hearing about whether calls on campus for the genocide of Jews would violate the school’s conduct policy.