Police were deployed in force on the University of California in Los Angeles (UCLA) campus on Wednesday morning after Israel supporters attacked a camp set up by pro-Palestinian protesters.

Witness footage from the scene, verified by Reuters, showed people wielding sticks or poles to attack wooden boards being held up as a makeshift barricade to protect the pro-Palestinian protesters, some of whom held placards or umbrellas.

On the other side of the country, police in New York arrested dozens of pro-Palestinian demonstrators holed up in a building at Columbia University and removed a protest encampment on Tuesday night.

New York City Mayor Eric Adams said about 300 people had been arrested and he blamed the protests on outside agitators, but without offering concrete evidence.

The October 7 attack on southern Israel by Hamas and the ensuing Israeli offensive in the Gaza Strip has unleashed the biggest outpouring of US student activism since the anti-racism protests of 2020.

As student rallies have spread to dozens of schools across the US in recent days expressing opposition to Israel’s military campaign in Gaza, police have been called in to quell or clear protests.

About 1,200 people in southern Israel were killed in the October 7 attack but the Israeli retaliatory assault has killed nearly 35,000 Palestinians, according to Gaza health ministry figures, obliterated much of the enclave’s infrastructure and created a humanitarian crisis verging on famine.

The student protests in the United States have also taken on political overtones in the run-up to the presidential election in November, with Republicans accusing some university administrators of turning a blind eye to antisemitic rhetoric and harassment.

On Tuesday, school officials informed the protesters that the encampment was unlawful and violated university policy. UCLA Chancellor Gene Brock said it included people “unaffiliated with our campus”.

Footage from the early hours showed mostly masked counter-demonstrators throwing objects and trying to smash or pull down the wooden and steel barriers erected to shield the encampment as pro-Palestinian protesters tried to fight them off. Demonstrators on both sides sprayed each other and fights broke out.

The Los Angeles Police Department said it had responded to a request from UCLA to restore order and maintain public safety “due to multiple acts of violence within the large encampment on their campus”.

Broadcast footage later showed a police cordon clearing a central quad beside the encampment. By 5am local time, they had erected a metal crowd barrier in front of the encampment and the area was quiet.

Los Angeles Councilwoman Katy Yaroslavsky, whose district includes UCLA, posted on X: “Everyone has a right to free speech and protest, but the situation on UCLA’s campus is out of control and is no longer safe.”

Columbia demonstrators arrested

On Tuesday night, New York City police had arrested dozens of pro-Palestinian demonstrators holed up in a building at Columbia University and removed a protest encampment that the Ivy League school had sought to dismantle for nearly two weeks.

Officers climbed into Hamilton Hall, which protesters had occupied in the early hours of Tuesday, through a second-storey window. Within three hours, they had cleared the protesters and arrested dozens, a police spokesperson said.

Columbia President Minouche Shafik asked police to stay on campus until at least May 17 — two days after graduation — to maintain order and ensure that encampments were not set up again.

Students standing outside the hall — the site of various student occupations dating back to the 1960s — jeered at police with shouts of “Shame, shame!”.

Police were seen loading dozens of detainees onto a bus, with their hands bound behind their backs by zip-ties, the scene illuminated with the flashing red and blue lights of police vehicles.

“Free, free, free Palestine!” protesters chanted outside the building. Others yelled, “Let the students go!”.

Sueda Polat of Columbia University Apartheid Divest, the coalition of student groups that organised the protests, said they did not pose a danger and urged police to back down.

Protesters accused of vandalism and trespass

Shafik said the Hamilton Hall occupiers had vandalised university property and were trespassing. The university earlier warned that students taking part in the occupation faced academic expulsion.

A few hours before police entered Columbia, Adams and police officials said the Hamilton Hall takeover had been instigated by “outside agitators” unaffiliated with Columbia. Adams provided no evidence.

One student protest leader, Mahmoud Khalil, a Palestinian scholar attending Columbia’s School of International and Public Affairs, disputed the assertion.

Police were also called in to clear encampments and make arrests overnight at Tulane University in New Orleans, University of Arizona and City College of New York in Harlem. Dozens were arrested at City College, The New York Times reported.

UCLA is part of the University of California system. It has about 32,000 undergraduate students and is located in the residential neighbourhood of Westwood just outside of Hollywood and downtown Los Angeles.