Hundreds of helmeted police have muscled their way into a central plaza of the University of California at Los Angeles to disperse a pro-Palestinian protest camp attacked the previous night by pro-Israel supporters.
The pre-dawn police crackdown at UCLA marked the latest flashpoint for mounting tensions on US college campuses, where protests over Israel's conduct of the war in Gaza have led to student clashes with each other and law enforcement.
Starting about sunset on Wednesday, officers in tactical gear began filing onto the UCLA campus next to a complex of tents occupied by throngs of demonstrators, live footage from the scene showed.
Police have torn down tents at the encampment where up to 500 people were hunkered down. (AP PHOTO)
Local television station KABC-TV estimated 300 to 500 were hunkered down inside the camp, while about 2000 more had gathered outside the barricades in support.
But the assembled police stood by on the periphery of the tents for hours before finally starting to force their way into the encampment about 3am on Thursday to arrest occupants who refused to leave.
Demonstrators, some carrying makeshift shields and umbrellas, sought to block the officers' advance by their sheer numbers, while shouting "Push them back" and flashing bright lights in the eyes of the police.
Some protesters had been seen donning hard hats, goggles and respirator masks in anticipation of the siege a day after the university declared the encampment unlawful.
Hundreds of other pro-Palestinian activists who assembled outside the tent city jeered police with shouts of "Shame on you" as officers marched onto the campus grounds.
A much smaller group of demonstrators waving Israeli flags urged on the police to shut down the encampment, yelling, "Hey hey, ho-ho, the occupation has got to go."
Before moving in, police urged demonstrators in repeated loudspeaker announcements to clear the protest zone, occupying a plaza between the landmark auditorium Royce Hall and the main undergraduate library.
UCLA had cancelled classes for the day following a violent clash between the encampment's occupants and a group of masked counter-demonstrators who mounted a surprise assault late on Tuesday night on the tent city.
The UCLA protest is one of many that have sprung up across US college campuses. (EPA PHOTO)
The occupants of the outdoor protest camp, set up last week, had remained otherwise peaceful before the melee, in which both sides traded blows and doused each other with pepper spray.
Members of the pro-Palestinian group said fireworks were thrown at them and they were beaten with bats and sticks.
University officials blamed the disturbance on "instigators" and vowed an investigation.
The confrontation went on for two or three hours into early Wednesday morning before police restored order.
A spokesperson for California Governor Gavin Newsom later criticised the "limited and delayed campus law enforcement response" to the unrest as "unacceptable".
UCLA officials said the campus, which enrols nearly 52,000 students, would remain shuttered on Thursday and Friday.
Wednesday night's police action came a day after police in New York City arrested pro-Palestinian activists who occupied a building at Columbia University and removed a tent city from its campus.
Police arrested about 300 people at Columbia and City College of New York, Mayor Eric Adams said.
Earlier, New York police arrested activists who occupied a building at Columbia University. (AP PHOTO)
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.
Ninety pro-Palestinian demonstrators - students and outsiders - were arrested at Dartmouth University in New Hampshire on Wednesday, the Hanover Police Department said.
They were charged with criminal trespass and resisting arrest.
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, calling for an immediate ceasefire 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.
The demonstrations across the country have been met with counter-protesters accusing them of fomenting anti-Jewish hatred.