New York (AP) ― Colleges around the U.S. implored pro-Palestinian student protesters to clear out tent encampments with rising levels of urgency Monday as police arrested more demonstrators at the University of Texas and Columbia University said it was beginning to suspend students who defied an ultimatum to disband the encampment there.

Dozens of law enforcement officers, many in riot gear, confronted protesters who returned to the University of Texas at Austin on Monday. They quickly arrested six demonstrators and took others into custody one by one. Officers used pepper spray after a group of protesters blocked the path of a police van carrying demonstrators who were arrested. The crowd backed away but continued to block the exit from campus. Officers then used two flash bang explosives to clear a path so the van could leave.

Republican Gov. Greg Abbott reposted on social media video of troopers arriving on the 50,000-student campus. “No encampments will be allowed," Abbott said. Just last week, hundreds of police pushed into protesters at the university, arresting 34 people.

At Columbia, student activists defied a 2 p.m. deadline to leave an encampment of around 120 tents on the school’s Manhattan campus. Instead, hundreds of protesters marched around the quad, clapping, chanting and weaving around piles of temporary flooring and green carpeting meant for graduation ceremonies that are supposed to begin next week.

A handful of counter-demonstrators waved Israeli flags, and one held a sign reading, “Where are the anti-Hamas chants?”

The university didn’t call police to roust the demonstrators. But three hours after the deadline passed, school spokesperson Ben Chang said Columbia had begun suspending students. He didn’t indicate how many students were involved. He also didn't say how the suspensions would be carried out or whether suspended students would be ejected from the campus.

Chang said that while the university appreciated the free speech rights of students, the encampment was a “noisy distraction” that was interfering with teaching and preparation for for final exams. The protests also made some Jewish students deeply uncomfortable, he said.

Protest organizers said they were not aware of any suspensions as of Monday evening.

The notice sent to protesters earlier Monday said if they left by the deadline and signed a form committing to abide by university policies through June 2025, they could finish the semester in good standing. If not, the letter said, they would be suspended, pending further investigation.

Early protests at Columbia sparked similar pro-Palestinian protest encampments at schools across the U.S. Students and others have been sparring over the Israel-Hamas war and its mounting death toll. Many students are demanding their universities cut financial ties with Israel. The number of arrests at campuses nationwide is approaching 1,000. The protests have even spread to Europe, with French police removing dozens of students from the Sorbonne university after pro-Palestinian protesters occupied the main courtyard.

College classes are wrapping up for the semester, and campuses are preparing for graduation ceremonies, giving schools an extra incentive to clear encampments. The University of Southern California canceled its main graduation ceremony.

But students dug in their heels at some high-profile universities, with standoffs also continuing at Harvard, the University of Pennsylvania, Yale and others.

Protesters at Yale set up a new camp with dozens of tents Sunday, nearly a week after police arrested nearly 50 and cleared a similar one nearby. They were notified by a Yale official that they could face discipline, including suspension, and possible arrest if they continued.

Yale said in a statement Monday that while it supports peaceful protests and freedom of speech, it does not tolerate policy violations such as the encampment. School officials said that the protest is near residential colleges where many students are studying for final exams, and that permission must be granted for groups to hold events and put up structures on campus.

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, 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 Brown University in Rhode Island, school President Christina H. Paxton offered protest leaders the chance to meet with officials to discuss their arguments for divestment from Israel-linked companies in exchange for ending an encampment.

In the letter to student protesters at Columbia, school officials noted that exams are beginning and graduation is upcoming.

“We urge you to remove the encampment so that we do not deprive your fellow students, their families and friends of this momentous occasion,” the letter said.

The demonstrations have led Columbia to hold remote classes. The school said in an email to students that bringing back police “at this time” would be counterproductive. The university said it will offer an alternative venue for the protests after exams and graduation.

Columbia's handling of the protests 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 U.S. 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.

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.

Demonstrators on other campuses, meanwhile, said they would stand firm. Jacob Ginn, a second-year University of North Carolina sociology graduate student, said he had been protesting at the encampment for four days, including negotiations with administrators Friday.

“We are prepared for everything and we will remain here until the university meets our demands and we will remain steadfast and strong in the face of any brutality and repression that they try to attack us with,” Ginn said in reference to a potential police sweep of the encampment.

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Mattise reported from Nashville, Tennessee. Associated Press journalists around the country contributed to this report, including Jim Vertuno in Austin, Texas; Sarah Brumfield in Silver Spring, Maryland; Christopher Weber in Los Angeles; Carolyn Thompson in Buffalo, New York; David Collins in Hartford, Connecticut; Makiya Seminera in Chapel Hill, North Carolina; and Corey Williams in Detroit.