Twenty-five people were arrested Saturday for trespassing at the University of Virginia after police clashed with pro-Palestinian protesters who refused to remove tents from campus, and demonstrators at the University of Michigan chanted anti-war messages and waved flags during commencement ceremonies.

In Virginia, student demonstrators began their protest on a lawn outside the school chapel Tuesday. On Saturday, video from WVAW-TV showed police wearing heavy gear and holding shields lined up on the campus in Charlottesville. Protesters chanted “Free Palestine,” and university police said on the social platform X that an “unlawful assembly” had been declared in the area.

As police moved in, students were pushed to the ground, pulled by their arms and sprayed with a chemical irritant, Laura Goldblatt, an assistant professor of English and global studies who has been helping student demonstrators, told The Washington Post.

“Our concern since this began has been the safety of our students. Students are not safe right now,” Goldblatt said.

The university administration said in a statement that the demonstrators were told the tents and canopies they erected were prohibited under school policy and were asked to remove them. Virginia State Police were asked to help with enforcement, the university said.

It was the latest clash in several tense and sometimes violent weeks at colleges and universities around the country that have seen dozens of protests and hundreds of arrests at demonstrations over the ongoing Israel-Hamas war.

Tent encampments of protesters calling on universities to stop doing business with Israel or companies they say support the war in Gaza have spread across campuses nationwide in a student movement unlike any other this century. Some schools have reached agreements with protesters to end the demonstrations and reduce the possibility of disrupting final exams and commencements.

The Associated Press has recorded at least 61 incidents since April 18 in which arrests were made at protests, with more than 2,400 people being arrested on 47 campuses. The figures are based on AP reporting and statements from universities and law enforcement agencies.

Many encampments have been dismantled.

Michigan was among the schools bracing for protests during commencement this weekend, including Indiana University, Ohio State University and Northeastern University in Boston. Many more are slated in the coming weeks.

In Ann Arbor, the protest happened at the beginning of the event at Michigan Stadium. About 75 people, many wearing traditional Arabic kaffiyehs along with their graduation caps, marched up the main aisle toward the graduation stage.

They chanted “Regents, regents, you can’t hide! You are funding genocide!” while holding signs, including one that read: “No universities left in Gaza.”

Overhead, planes flew banners with competing messages. “Divest from Israel now! Free Palestine!” and “We stand with Israel. Jewish lives matter.”

Officials said no one was arrested, and the protest didn’t seriously interrupt the nearly two-hour event, which was attended by tens of thousands of people, some of them waving Israeli flags.

State police prevented the demonstrators from reaching the stage and university spokesperson Colleen Mastony said public safety personnel escorted the protesters to the rear of the stadium, where they remained through the conclusion of the event.

“Peaceful protests like this have taken place at U-M commencement ceremonies for decades,” she added.

The university has allowed protesters to set up an encampment on campus, but police assisted in breaking up a large gathering at a graduation-related event Friday night, and one person was arrested.

At Indiana, protesters were urging supporters to wear their kaffiyehs and walk out during remarks by President Pamela Whitten on Saturday evening. The Bloomington campus designated a protest zone outside Memorial Stadium, the arena for the ceremony.

At Princeton, in New Jersey, 18 students launched a hunger strike in an effort to push the university to divest from companies tied to Israel.

One of them, senior David Chmielewski said in an email that the strike started Friday morning with participants consuming water only, and it will continue until administrators meet with students about demands including amnesty from criminal and disciplinary charges for protesters.

Other demonstrators are participating in “solidarity fasts” lasting 24 hours, Chmielewski said.

Princeton students set up a protest encampment and some held a sit-in at an administrative building this week, leading to about 15 arrests.

Students at other colleges, including Brown and Yale, launched similar hunger strikes earlier this year before the more recent wave of encampments.

Meanwhile in Medford, Massachusetts, students at Tufts University peacefully took down their encampment without police intervention Friday night.

School officials said they were pleased with the development, which wasn’t the result of any agreement. Protest organizers said in a statement that they were “deeply angered and disappointed” that negotiations with the university had failed.

The protests stem from the conflict that started Oct. 7 when Hamas militants attacked southern Israel, killing about 1,200 people, mostly civilians, and taking roughly 250 hostages.

Vowing to destroy Hamas, Israel launched an offensive in Gaza that has killed more than 34,500 Palestinians, around two-thirds of them women and children, according to the Health Ministry in the Hamas-ruled territory. Israeli strikes have devastated the enclave and displaced most of its inhabitants.

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Marcelo reported from New York. Lavoie reported from Richmond, Virginia. Associated Press reporters Ed White in Detroit, Nick Perry in Boston and Adrian Sainz in Memphis, Tennessee, contributed.