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.

New York University and New School, in separate statements, said they requested police move students from their campuses after multiple rounds of negotiations failed.

NYU said the "encampment had become increasingly untenable for the NYU community and the neighborhood we inhabit." Classes will proceed as normal today.

NYU said it is aware of calls for a 4 p.m. protest at the former site of the encampment.

The New School, which switched to remote learning Friday, said students continued to set up in the lobby of the University Center building and block access to the "residence hall, classrooms, library, and cafeteria."

Despite the university "pleading to allow their fellow students to enter their residence hall, the protesters would not budge."

The New School said the protests continued even after they "provided a confirmed date this month for the Investment Committee to consider a vote on disinvestment."

"It is a sad day for all of us who are part of this university community and who believe in free speech, which we have pledged to protect and will continue to protect," The New School said in a statement.