Police in riot gear have been forced to break up protesters at a California university hours after Columbia University in New York was raided.

Protests over the Israel-Hamas war reached boiling point at US universities overnight. Hundreds of campus protesters have been arrested across the country over the past week.

The clashes on the University of California, Los Angeles (UCLA) campus took place early on Wednesday morning outside a tent encampment, where pro-Palestinian protesters erected barricades and plywood for protection, which counter-protesters tried to pull down. The protesters shoved and kicked one another, sometimes beating people with sticks or throwing chairs.

Read more:Why are students protesting? The LA mayor Karen Bass wrote on X: "The violence unfolding this evening at UCLA is absolutely abhorrent and inexcusable. "LAPD has arrived on campus." In a statement on X, the LAPD said: "At the request of UCLA, due to multiple acts of violence within the large encampment on their campus, the LAPD is responding to assist UCLA PD, and other law enforcement agencies, to restore order and maintain public safety." Sky News US correspondent Martha Kelner, reporting from the university site in Los Angeles, said: "Just look at this scene on a US university campus - California highway patrol wearing riot shields, riot masks, gas masks underneath their helmets." She said they were wearing gas mask "because throughout the course of the evening from inside this encampment, or at least the vicinity, a substance was released, I think, probably, pepper spray".

"But the police here are not taking any chances, wearing gas masks - preparing, I guess, potentially to access this encampment." She reported how a protester appeared to pray at the feet of officers, adding: "She's a pro-Palestinian protester. She's refusing to move for the California Highway Patrol.

She appears to be kneeling down, perhaps in prayer, at the feet of the patrol. "It is a remarkable sight to see.

These are scarcely fathomable scenes on a US university campus." By 5am local time, she reported how the "volatile" situation at the campus had calmed down. "This is still a fluid, evolving situation - but it is much calmer here.

There are a couple of groups of police officers, but otherwise the police lines seem to have moved back," she added. "They've created a barrier between the outside world, if you like, and the encampment of pro-Palestinian supporters beyond all of the counter-protesters, or at least the vast majority, who were the pro-Israel supporters.

They have been cleared from the vicinity. "The question is, what now happens to this encampment of students and others who are pro-Palestine? Will they be forcibly moved on or will the police decide that they can remain here?" Riot police raid Columbia University On the other side of the country, police in riot gear raided Columbia University and arrested pro-Palestinian protesters occupying one of its buildings.

About 30 to 40 people were removed from the Manhattan university's Hamilton Hall, according to police. The raid came hours after New York City Mayor Eric Adams said the demonstration at the Ivy League school "must end now".

He also claimed the demonstration had been infiltrated by "professional outside agitators". University bosses said they called in the New York Police Department (NYPD) after protesters "chose to escalate the situation through their actions".

"After the university learned overnight that Hamilton Hall had been occupied, vandalised, and blockaded, we were left with no choice," a university spokesman said in a statement. "The decision to reach out to the NYPD was in response to the actions of the protesters, not the cause they are championing.

"We have made it clear that the life of campus cannot be endlessly interrupted by protesters who violate the rules and the law." Those behind the protest said they had renamed the building "Hind's Hall" in honour of Hind Rajab, a six-year-old girl killed in a strike on Gaza in February. Demonstrators said they had planned to remain at the hall until the university conceded to the Columbia University Apartheid Divest's (CUAD) three demands: divestment, financial transparency and amnesty.

"Columbia will be proud of these students in five years," said Sweda Polat, one of the student negotiators for CUAD. A large group of officers dressed in riot gear entered the campus late on Tuesday evening.

Officers were also seen entering the window of a university building via a police-branded ladder vehicle, nicknamed "the bear". Earlier, Mayor Adams urged demonstrators to leave the site.

"Walk away from this situation now and continue your advocacy through other means," he said. Protests at Columbia earlier this month kicked off demonstrations which have spread to university campuses from California to Massachusetts.

Dozens of people were arrested on Monday during protests at universities in Texas, Utah, Virginia, and New Jersey. Read more from Sky News:US plans to reclassify cannabis as less dangerous drugFour police officers shot dead in North Carolina Meanwhile, the president of the University of South California issued a statement on Tuesday after a swastika was drawn on the campus.

"I condemn any antisemitic symbols or any form of hate speech against anyone," Carol Folt said. "Clearly it was drawn there just to incite even more anger at a time that is so painful for our community.

We're going to work to get to the bottom of this immediately, and it has just been removed." Earlier, National Security Council spokesperson John Kirby said President Joe Biden believed students occupying buildings was "absolutely the wrong approach" and "not an example of peaceful protest"..