Eyewitness videos from the UCLA, verified by Reuters, showed people wielding sticks or poles to hammer on wooden boards being used as makeshift barricades to protect the pro-Palestinian protesters before police were called to the campus.
The university cancelled classes for the day on Wednesday, and Chancellor Gene Block said the school would conduct an investigation "that may lead to arrests, expulsions and dismissals".
Pro-Palestianian protesters gather near a main gate at Columbia University in New York. (AP PHOTO)
In a statement, Block said the "appalling" assault on pro-Palestinian demonstrators, which came hours after their encampment was declared an unlawful assembly by UCLA, was committed "by a group of instigators".
In New York City, scores of police officers in helmets and tactical gear arrested pro-Palestinian demonstrators occupying Hamilton Hall, an academic building at Columbia University.
Undergraduate students watching the extraordinary scene, many jeering at the police, fled into nearby buildings as police also cleared out a nearby protest encampment that had inspired similar protests at campuses across the country and abroad.
Police arrested about 300 people at Columbia and City College of New York, Mayor Eric Adams said. Many of those arrested were charged with trespassing and criminal mischief.
The clashes at UCLA and in New York were part of the biggest outpouring of US student activism since the anti-racism rallies and marches of 2020.
The protests follow the October 7 attack on southern Israel by Hamas militants from the Gaza Strip and the ensuing Israeli offensive on the Palestinian enclave.
Students have rallied or set up tent encampments at dozens of schools across the US in recent days, expressing opposition to Israel's war in Gaza and demanding schools divest from companies that support Israel's government. Many of the schools have called in police to quell the protests.
With the presidential election coming in November, Republican lawmakers have accused some university administrators of ignoring antisemitic rhetoric and harassment, and some have demanded Columbia's President Minouche Shafik resign.
Many protesters, some of whom are Jewish, reject allegations of antisemitism. Shafik has said the protests brought rancour to life at Columbia and created a "threatening environment" for many Jewish students and faculty, while also blaming some episodes of harassment and hostile rhetoric on outsiders drawn to the busy Manhattan streets surrounding the campus.
People gather in support of the encampment of pro-Palestinian protesters on the UCLA campus. (EPA PHOTO)
US President Joe Biden, who has angered many protesters by funding and arming Israel, plans to give a speech on antisemitism next week at a Holocaust memorial event.
"Americans have the right to peacefully protest," Karine Jean-Pierre, the White House spokesperson, told reporters.
"Forcibly taking over a building is not peaceful."
Republican US presidential candidate Donald Trump praised the police raid Columbia's campus, saying it "was a beautiful thing to watch". He called the ousted protesters "raging lunatics and Hamas sympathisers".
Before the clashes in Los Angeles, UCLA officials declared that an encampment on its campus was unlawful, violated university policy and included people unaffiliated with the campus.
Afterwards, counter-demonstrators - many of them masked and some apparently older than most students - can be seen in videos throwing objects and trying to smash or pull down the wooden and steel barriers erected to shield the encampment.
Due to distress following the violence on Royce Quad & ongoing tension regarding campus demonstrations, UCLA First Thursdays, on May 2, has been canceled. We must all protect the wellbeing of our peers & maintain a safe learning environment. — UCLA (@UCLA) https://t.co/X91FIH8vWK pic.twitter.com/HzT8rIeAfYMay 1, 2024
Police said UCLA had called them to restore order and maintain public safety within the encampment. Video later showed police clearing a central quad beside the encampment and erecting a metal crowd-control barrier in front of it.
The atmosphere was calmer on Wednesday. Hundreds of police officers were on campus and lining its perimeter. It was unclear how many arrests were made or the number of people injured.
The university earlier warned that students involved in the occupation faced academic expulsion.
