Video footage showed protesters on Columbia's Manhattan campus locking arms in front of Hamilton Hall early Tuesday and carrying furniture and metal barricades to the building, one of several that was occupied during a 1968 civil rights and anti-Vietnam War protest on the campus.

Posts on an Instagram page for protest organizers shortly after midnight urged people to protect the encampment and join them at Hamilton Hall.

The student radio station, WKCR-FM, broadcasted a play-by-play of the hall's takeover – which occurred nearly 12 hours after Monday's 2 p.m. deadline for the protesters to leave an encampment of around 120 tents or face suspension.

Representatives for the university did not immediately respond to emails requesting comment early Tuesday.

Universities across the US are grappling with how to clear out encampments as commencement ceremonies approach, with some continuing negotiations and others turning to force and ultimatums that have resulted in clashes with police.

Dozens of people were arrested on Monday during protests at universities in Texas, Utah and Virginia, while Columbia said hours before the takeover of Hamilton Hall that it had started suspending students.

Demonstrators are sparring over the Israel-Hamas war and its mounting death toll, and the number of arrests at campuses nationwide is approaching 1,000 as the final days of class wrap up. The outcry is forcing colleges to reckon with their financial ties to Israel, as well as their support for free speech. Some Jewish students say the protests have veered into antisemitism and made them afraid to set foot on campus.

At the University of Texas at Austin, an attorney said at least 40 demonstrators were arrested Monday. The confrontation was an escalation on the 53,000-student campus in the state's capital, where more than 50 protesters were arrested last week.

Later Monday, dozens of officers in riot gear at the University of Utah sought to break up an encampment outside the university president's office that went up in the afternoon. Police dragged students off by their hands and feet, snapping the poles holding up tents and zip-tying those who refused to disperse. Seventeen people were arrested. The university says it's against code to camp overnight on school property and that the students were given several warnings to disperse before police were called in.

The plight of students who have been arrested has become a central part of protests, with the students and a growing number of faculty demanding amnesty for protesters. At issue is whether the suspensions and legal records will follow students through their adult lives.

The Texas protest and others — including in Canada and Europe — grew out of Columbia's early demonstrations that have continued. On Monday, student activists defied the 2 p.m. deadline to leave the encampment. Instead, hundreds of protesters remained. A handful of counter-demonstrators waved Israeli flags, and one held a sign reading, “Where are the anti-Hamas chants?”

While the university didn't call police to roust the demonstrators, school spokesperson Ben Chang said suspensions had started but could provide few details. Protest organisers said they were not aware of any suspensions as of Monday evening.

Columbia's handling of the demonstrations also has prompted federal complaints.

A class-action lawsuit on behalf of Jewish students alleges a breach of contract by Columbia, claiming the university failed to maintain a safe learning environment, despite policies and promises. It also challenges the move away from in-person classes and seeks quick court action requiring Columbia to provide security for the students.

Meanwhile, a legal group representing pro-Palestinian students is urging the US Department of Education's civil rights office to investigate Columbia's compliance with the Civil Rights Act of 1964 for how they have been treated.

A university spokesperson declined to comment on the complaints.

In a rare case, Northwestern University said it reached an agreement with students and faculty who represent the majority of protesters on its campus near Chicago. It allows peaceful demonstrations through the June 1 end of spring classes and in exchange, requires removal of all tents except one for aid, and restricts the demonstration area to allow only students, faculty and staff unless the university approves otherwise.

At the University of Southern California, organisers of a large encampment sat down with university President Carol Folt for about 90 minutes on Monday. Folt declined to discuss details but said she heard the concerns of protesters and talks would continue on Tuesday.

USC sparked a controversy April 15 when officials refused to allow the valedictorian, who has publicly supported Palestinians, to make a commencement speech, citing nonspecific security concerns for their rare decision.

Administrators then scrapped the keynote speech by filmmaker Jon M. Chu, who is an alumnus, and declined to award any honorary degrees.

The backlash, as well as Columbia's demonstrations, inspired the encampment and protests on campus last week week where 90 people were arrested by police in riot gear. The university has cancelled its main graduation event.

Administrators elsewhere tried to salvage their commencements and several have ordered the clearing of encampments in recent days. When those efforts have failed, officials threatened discipline, including suspension, and possible arrest.

But students dug in their heels at other high-profile universities, with standoffs continuing at Harvard, the University of Pennsylvania, Yale and others. Police in riot gear at Virginia Commonwealth University sought to break up an encampment there late Monday and clashed with protesters.