It was an example of a tolerant campus, where a burgeoning pro-Palestinian encampment might be left alone even as student protesters were arrested across the nation. Free speech would be supported as long as things remained peaceful, officials said last week.

But by Wednesday morning, the peace at the University of California, Los Angeles, had been shattered. The university cancelled classes for the day, pushed back midterms and scrambled to address an overnight eruption of bloody violence spurred by dozens of counterprotesters.

The melee, which continued for hours without intervention, was a display of fierce hostility as fistfights broke out, chemicals were sprayed into the air and people were kicked or beaten with poles. Many participants did not appear to be students.

“They had bear spray, they had mace, they were throwing wood-like spears, throwing water bottles,” said Marie Salem, 28, a graduate student and pro-Palestinian protester who was part of the encampment. “They set off fireworks toward our camp directly. And so, we were all hands on deck, just guarding our barricades.”

Now, there is widespread frustration over UCLA’s handling of the incident, and the university faces scrutiny for its delayed response to the drawn-out chaos. Many critics were incredulous that even after officers with the Los Angeles Police Department arrived, there were no arrests or suspensions.

On Wednesday evening, campus officials ordered protesters to leave the encampment or face arrest. A stream of students departed, but hundreds remained around 7 p.m. and donned helmets, masks and goggles. Dozens of police officers were stationed around the protest site.

The school abides by a University of California policy that avoids involving law enforcement unless “absolutely necessary to protect the physical safety of our campus community.” But the coming days will test UCLA as it navigates its ideals, the presence of city police newly embedded on its campus, and heightened tension.

“There’s a sense that the other side has immunity,” Salem said as a police helicopter hovered above. Around her, the landscape was littered with trash, splintered wood, trampled clothing. A large Palestinian flag fluttered in the air. Students and faculty members had been urged to stay away from the area.

“The general response from the student body is just frustration,” said Aidan Woodruff, 19, a freshman majoring in cello performance. He said he knew at least 50 students who had spent the past two days studying for midterms only to learn that the exams were postponed. The last week had already been a source of aggravation for those trying to focus on academics but confronted by protesters using metal gates and human walls to control access to campus walkways.

“There are definitely students who feel strongly about the causes, but a big part of it is people coming in from the general LA area and putting on a demonstration here that’s causing so much disruption,” Woodruff said.

Friction at the university, where Jewish activists have had a larger presence than at other demonstrations, had been simmering since Sunday when a pro-Israel rally planted itself about 20 feet from the encampment.

A day later, tension mounted after reports that a Jewish student had been blocked by the pro-Palestinian group as he tried to get to the nearby library. Campus police had to intervene when about 60 pro-Israel demonstrators tried to enter the encampment and a fight broke out.

By 4 p.m. Tuesday, the administration’s approach abruptly shifted. Gene Block, the UCLA chancellor, declared the encampment an unlawful assembly and shut down the library and Royce Hall, the two main buildings near it.

“UCLA supports peaceful protest, but not activism that harms our ability to carry out our academic mission and makes people in our community feel bullied, threatened and afraid,” Block said in a statement. “These incidents have put many on our campus, especially our Jewish students, in a state of anxiety and fear.”

An alert informed students and employees that they could face serious sanctions, including discipline and potential dismissal for students, if they stayed.

At about 11 p.m., pro-Israel counterprotesters began trying to tear down an encampment barricade erected of metal gates, plywood and beach umbrellas, according to city officials. Shortly thereafter, they set off fireworks directly above the encampment. Videos on social media showed the firecrackers exploding near demonstrators and people spraying what appeared to be chemical irritants at one another.

Campus police were on the scene at that point and more arrived, along with university paramedics. But UCLA seemed to wait too long to call in the Los Angeles police, whose officers did not arrive until after midnight.

Just before 1 a.m. Wednesday, Mayor Karen Bass’ office issued a statement that officers with the city would be responding to a request for support from the school. An hour later, she said on social media that the Police Department, which does not have jurisdiction over the campus, had arrived on the scene. Counterprotesters chanted “Back the blue.”

California Highway Patrol officers arrived on campus at about 1:15 a.m., according to Officer Michael Nasir, a spokesperson.

By around 3:30 a.m., the authorities had wedged themselves into the fray and things began to de-escalate.

In a statement 12 minutes after midnight Wednesday, Mary Osako, a vice chancellor at the university, said law enforcement had been immediately called for mutual aid support. “We are sickened by this senseless violence and it must end.”

But the UCLA Palestinian Solidarity Encampment, which says it is made up of students, faculty members and community members, condemned the school’s “pretense of student safety” in a statement, saying that campus police, external security and law enforcement failed to protect them from counterprotesters as “we screamed for their help.”

And Katy Yaroslavsky, the city council member representing the neighborhoods around UCLA, called the response from its campus police “too slow and ineffective in protecting student safety.”

“In failing to control the situation, students and others on campus were left vulnerable to violence that has no place on our college campuses,” she said in a statement.

While the mayor called for a full investigation and the president of the UC system ordered an independent review, the authorities combed through footage recorded on cellphones and additional cameras. Others took it upon themselves to identify the worst of the perpetrators by circulating footage with magnified stills.

Major Jewish and Muslim organizations condemned the attack. The greater Los Angeles area is home to the second-largest concentration of Jews in the nation, with significant Jewish communities around the Westside region, which includes UCLA.

Beverly Hills, for instance, has one of the largest communities of Iranian Jews in the nation, while the Fairfax District has such a large community of Orthodox Jews that the city created a special, no-touch “sabbatical” streetlight for them in the 1970s so that they would not have to disobey religious edicts against activating electricity.

The Jewish Federation Los Angeles said that it was “appalled” at the violence that occurred on campus, and that the counterprotesters did not represent the Jewish community or its values. The federation criticized Block, the UCLA chancellor, and the school’s administration for creating an environment that has made students feel unsafe and called on him to meet with Jewish community leaders to discuss safety measures.

Hussam Ayloush, the director of the Greater Los Angeles Area office of the Council on American-Islamic Relations, urged Rob Bonta, the state’s attorney general, to investigate what he characterized as a lack of response by campus police and the Los Angeles Police Department.

“UCLA and other schools must ensure that students can continue to peacefully protest the genocide in Gaza without facing attacks by violent pro-Israel mobs,” Ayloush said in a statement.

The extreme shift on campus has been hard to comprehend for many, and students who watched what happened on social media or were in touch with those on the ground found it devastating to watch things escalate.

“I think I had allowed myself to be lulled into a false sense of good vibes, and that people were handling themselves,” said Benjamin Kersten, 31, an art history doctoral candidate who has been organizing with the Los Angeles and UCLA chapters of Jewish Voice for Peace. He noted that the university’s hands-off approach ended up being a double-edged sword.

On Wednesday morning, Bella Brannon, the editor-in-chief of the university’s Jewish newsmagazine, was trying to make sense of the footage she had seen.

“What happened was clearly and flatly wrong, immoral, deliberate acts of violence against students,” she said. “I am especially worried that their actions will cloud dialogue with the pro-Israel community.”

Brannon, 21, is majoring in public affairs and the study of religion and has friends who are protesting in support of Palestine. In recent days, she has been disturbed by the protests on both sides of the conflict.

“The college campus is a nonstop hub for discourse, even if it’s incendiary. I can’t go home and take a bath and relax and forget about it,” she said. “For us, there is no separation between school and home — it’s always everything, all at once.”

The New York Times News Service