California Highway Patrol officers in riot gear streamed early Thursday onto the University of California Los Angeles campus.

The officers were met by a wall of protesters, who appeared unwilling to move. Officials had earlier ordered protesters to abandon their encampment.

Officers were working to tear down barricades of plywood boards that been erected along some of the edges of that encampment.

Los Angeles Police Department officers had earlier retreated from the encampment. At one point, LAPD and protesters briefly scuffled as officers made their way out of the encampment.

-ABC News' Amanda Morris and Kevin Shalvey

At least 90 people were arrested Wednesday during a protest on the campus of Dartmouth University, local police said.

The people who were arrested included both students and non-students, Hanover Police Department said in a statement released Thursday. Charges included criminal trespass and resisting arrest, police said.

Ahead of Wednesday's planned protest, campus security had warned demonstrators that tents or encampments wouldn't be allowed.

"Once tents were erected, Dartmouth Safety & Security made multiple announcements to participants that they must dispel, and they refused," Charles B. Dennis, Hanover's chief of police, said in a media release.

Hanover police and the New Hampshire State Police continued with "multiple" announcements, but some protesters refused to disperse, he said.

-ABC News' Jessica Gorman and Kevin Shalvey

UCLA's public safety department said in an alert Wednesday night that all on campus classes were "required to pivot to remote" through the end of the week.

The announcement comes after overnight protests turned violent, injuring 15 and sending one person to the hospital, university officials previously confirmed.

Campus operations will be limited on Thursday and Friday, the public safety department said in its evening update.

"We have a large law enforcement presence stationed throughout campus to help promote safety," the department said. "Student Affairs will have essential staff on campus to support our students."

Police at UCLA have announced to the gathered crowd that the encampment on campus is an "unlawful gathering."

Demonstrators have been ordered to leave by the LAPD, according to KABC 7.

UCLA is broadcasting a message of its own, telling protesters to disperse. The message, which appears to be recorded, says those who don't leave will be subject to administrative action.

The University of Minnesota has reached an agreement to end the student-led encampment on campus.

The university will reopen previously closed buildings and the student coalition has pledged not to organize disruptions during final exams and the commencement ceremony.

Representatives of the student coalition will be given the opportunity to address the Board of Regents at its May 10 meeting over its call for a divestment, students will receive amnesty for their encampment, and the university will also explore an affiliation with Palestinian universities, hosting scholars at risk.

"Our meetings have been grounded in listening, learning, and respect, and I believe they were a very positive first step in reaching mutual understanding. Though the original meeting was scheduled for 30 minutes yesterday, we engaged in constructive conversation for more than 90 minutes. We then met two more times to discuss the proposed agreements," University of Minnesota interim President Jeff Ettinger said in a statement.

"We regret that these meetings did not happen sooner, and have committed to regular meetings moving forward to continue to discuss this coalition’s concerns," Ettinger said.

Ettinger also highlighted that the university supports freedom of expression as a fundamental part of its mission.

"While we do not condone tactics that are outside of our policies, we appreciate student leaders’ willingness to engage in dialogue. I value the challenging and healthy conversations we’ve had," Ettinger said.