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.

Northwestern University announced it has reached a deal with pro-Palestinian protesters, ending an encampment of students and faculty, but allowing peaceful demonstrations to continue through June 1.

The university said it would "answer questions from any internal stakeholder about holdings, held currently or within the last quarter, to the best of its knowledge and to the extent legally possible" -- meeting a key call from divestment protesters and students around the country who are seeking more transparency over universities' investments.

Northwestern will also reestablish an Advisory Committee on Investment Responsibility in the fall, which will include representatives from students, faculty and staff.

The university also pledged more inclusivity, funding two Palestinian faculty members and the full cost of attendance for five Palestinian undergraduate students annually, as well as a commitment to raising funds to sustain the program beyond this commitment.

Under the agreement, Northwestern says tents will be removed immediately but one aid tent will be allowed to remain. Protesters will need to suspend the use of "non-approved" amplified sound." Protesters who refuse to follow the agreement will be suspended and non-affiliated individuals must leave campus.