A leading California university has canceled its graduation ceremony as protests over Gaza continue to spread on college campuses across the US. The University of Southern California (USC) in Los Angeles cited "new safety measures" in disbanding the event. Hundreds of people have been arrested on dozens of campuses where protests and encampments have sprung up in support of Palestinians in Gaza. Universities have brought in police to force students to leave. But some are also negotiating. At Columbia University in New York City, where the protests began last week, a Thursday night deadline for an end to the encampment was dropped. Talks were showing progress and would continue, the university said. At Atlanta"s Emory University, 28 demonstrators were arrested on Thursday after refusing to leave. Emory"s police force said protesters had "pushed past" officers protecting the area set up for commencement on Thursday morning. The force acknowledged that chemical irritants had been released as part of crowd control measures, though they said it was in response to objects being thrown at officers. Atlanta Police also confirmed using chemical irritants but denied reports they had fired rubber bullets at protesters. One protester shown on video being detained by police identified herself as Noelle McAfee, chair of Emory"s philosophy department. Ms McAfee said she was observing what she described as a peaceful protest when police began to move in and the protesters started to march. "It went from a peaceful protest to mayhem in the matter of a minute," she said. She said she had frozen and been quickly detained. The latest wave of campus protests began after officials at Columbia University called in police to clear a new protest encampment and more than 100 people were arrested. Activists have been calling for universities to "divest from genocide" and to stop investing large school endowments in companies involved in weapons manufacturing and other industries supporting Israel"s war in Gaza. Israel is currently facing a case brought by South Africa at the International Court of Justice alleging that it is committing genocide against the Palestinians, an accusation Israel has rejected as "baseless". Chisato Mimura, a law student and protest leader at Yale University in Connecticut, told the BBC that activists were upset at President Joe Biden as well as their school officials for "quite literally funding and equipping the weapons used in genocide". "What they"re doing is completely putting their full weight behind it," she said. "We are well aware of the prominent role they are playing." Some of the protests on US campuses have been accused of antisemitism. A number of Jewish students have said they have felt unsafe at Columbia and at other universities, although other Jewish students have joined the demonstrations. Earlier on Thursday, Minnesota Democratic congresswoman Ilhan Omar visited the campus. Her daughter, Isra Hirsi, was one of the protesters cleared from the university by police last week. "This is a movement that started with only 70 students," Ms Omar told the BBC. "And because Columbia University decided to crack down on them and violate their First Amendment [rights], this has now spread nationally and internationally." In other recent developments: In Syracuse, New York, President Biden was greeted by around 100 protesters with signs reading "Genocide Joe" and other slogans as he attended an official event A camp was set up at Northwestern University near Chicago, where school officials moved to limit the use of tents. Police were on campus and ordered protesters to leave, but no arrests were reported Organisers of the Uncommitted movement, which has encouraged Democratic primary voters to reject President Biden, said that they would join the student activists camping at the University of Michigan Students at Georgetown University, George Washington University and American University protested in Washington DC Brandeis University in Boston, where one-third of the student body is Jewish, said it would extend its transfer deadline to accommodate students who felt targeted and attacked at other schools California State Polytechnic University, Humboldt said its campus could remain closed until next week because of protesters occupying buildings Other campuses to see protests and encampments include Harvard, Brown, MIT and Indiana University The war began when Hamas-led gunmen carried out an unprecedented attack on southern Israel on 7 October, killing about 1,200 people — mostly civilians — and taking 253 others back to Gaza as hostages. More than 34,180 people — most of them children and women — have been killed in Gaza since then, the territory"s Hamas-run health ministry says. — BBC