Hundreds of police tore down protest barricades and began arresting students early Thursday at the University of California, Los Angeles -- the latest flashpoint in an eruption of protest on US campuses over Israel's war against Hamas in Gaza.

Officers in riot gear ripped down a wooden barricade around the protest encampment and dragged tents away in the fresh campus clashes, which for weeks have seen authorities attempt a tightrope walk between the right to protest and complaints of violence and hate speech.

Students clad in white helmets linked arms and formed a line facing off against officers, who were detaining protesters and leading them away.

Police used flashbangs to disperse the crowds gathered outside the encampment who were chanting "Let them go!" as helicopters hovered overhead.

Officers blocked stairs accessing the encampment, with students dressed in yellow jackets and serving as medics telling AFP they were being largely prevented from accessing the area.

On another side of the encampment students carrying umbrellas, helmets and plastic shields squared off against police in tense silence, with a few sporadic chants of "Free Palestine!" and "From the river to the sea, Palestine will be free!"

"This is a peaceful protest, there are no counter-protestors tonight, so to call the police on them is despicable. This city should support them," LA resident Jack Bedrosian, who came along to show support, told AFP.

The large police presence, including California Highway Patrol and LAPD officers, comes after law enforcement were criticized for being slow to act during violent clashes late Tuesday when counter-protesters attacked an encampment of pro-Palestinian students.

UCLA said classes would be remote on Thursday and Friday due to the "emergency on campus," and warned students to avoid the protest area.

- Wave of unrest -

Demonstrators have gathered in at least 30 US universities since last month, often erecting tent encampments to protest the soaring death toll in the Gaza Strip.

Police tore down a protest encampment at the University of Texas on Wednesday, arresting more than a dozen people.

Officers also detained several people at Fordham University in New York and cleared an encampment set up inside a school building, officials said.

At the Massachusetts Institute of Technology, protesters dug in, blocking an avenue near the center of the campus in Cambridge during the height of Wednesday afternoon's rush hour commute.

The University of Texas Dallas saw police remove an encampment and arrest at least 17 people for "criminal trespass," the school said.

At Columbia University and at the City University of New York, where police cleared out demonstrators overnight into Wednesday, some students decried the police behavior and described a litany of injuries, including "severe head traumas" and "concussions."

Police said about 300 arrests were made at Columbia and another New York university.

Mayor Eric Adams blamed "outside agitators" for ratcheting up tensions. Columbia students have denied outsiders were involved.

- Balancing act -

The protests have posed a challenge to university administrators trying to balance free speech rights with complaints of criminal activity, anti-Semitism and hate speech.

The administration of President Joe Biden -- whose support for Israel has outraged many protesters -- has also tried to walk that line, emphasizing the right to protest while decrying hate speech and anti-Semitism.

But Biden's rival in the November election, Donald Trump, has voiced his full-throated support for a crackdown.

"To every college president, I say remove the encampments immediately, vanquish the radicals and take back our campuses for all of the normal students," he told a rally in Wisconsin on Tuesday.

The Gaza war started when Hamas militants staged an unprecedented attack on Israel on October 7 that left around 1,170 people dead, mostly civilians, according to an AFP tally of Israeli official figures.

The militants also took about 250 hostages.

Israel's retaliatory offensive has killed more than 34,500 people in Gaza, mostly women and children, according to the Hamas-run territory's health ministry.