https://www.bbc.com/news/world-us-canada-68937775
Violence erupted at the University of California, Los Angeles after pro-Israeli counter-demonstrators attacked a pro-Palestinian campus encampment.
Bubbling tensions on the campus boiled over following the alleged breach of a "buffer zone" between the rival groups.
Fireworks and tear gas flew through the night sky as masked counter-protesters attempted to tear down barricades, and struck campers with sticks and bats.
Protesters have said that police were slow to respond after violence started.
Law enforcement called to the scene was guarding the space as morning broke.
The overnight clash at one of America's top public colleges took place only hours after police in New York had raided and cleared a Columbia University building taken over by students.
Protests at Columbia against the war in Gaza have inspired similar actions at universities - small and large, public and private - in more than two dozen states, with protesters demanding that institutions cut financial ties with Israel and companies profiting from the war.
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Mary Osako, a UCLA vice-chancellor, said police and other first responders were immediately called to the scene of its encampment over "horrific acts of violence" early on Wednesday morning.
"We are sickened by this senseless violence and it must end," she said.
Classes were cancelled on Wednesday.
The university declared the tent camp on Dickson Plaza an illegal gathering on Tuesday but declined to involve law enforcement in disrupting what it called a "largely peaceful" demonstration.
But the security presence in the area expanded over the past 48 hours as tensions flared between the encampment and pro-Israeli individuals, with the groups separated by a narrow buffer zone of barricades.
Footage online appears to show a large group of counter-protesters, donning black outfits and white masks, arriving on campus just before midnight on Tuesday and attempting to dismantle the barriers.