Clashes between opposing groups of protesters at the University of California Los Angeles included "multiple acts of violence," prompting university officials to ask police to enter the campus, the Los Angeles Police Department said.

Officers responded to assist campus police "to restore order and maintain public safety," the LAPD said.

State and local politicians said they were monitoring the situation, with Los Angeles Mayor Karen Bass calling the violence "absolutely abhorrent and inexcusable."

Gov. Gavin Newsom said his office had been in contact with law enforcement leadership.

-ABC News' Bonnie Mclean, Amanda Morris and Kevin Shalvey

At least 25 people were arrested at CUNY's City College of New York campus as police confronted protesters early Wednesday, the university said in a statement.

University officials said they asked the New York Police Department for assistance in clearing protesters, including a "large crowd" of people who had marched from Columbia University to City College.

The school described a "series of violent indents" that it said put public safety at risk over the last six days.

"This includes a fire Sunday night at the Marshak Science Building caused by use of a flare gun that brought FDNY to campus, clashes with public safety, an attempted break-in at Shepard Hall tonight, and a break-in at the Administration Building tonight that included the vandalizing of offices and smashing glass doors," the university said in a press release early Wednesday.

Police entered the campus just before midnight and began making arrests, the university said.

"Students have a right to demonstrate peacefully and exercise their First Amendment rights," the university said. "Tonight's actions were taken in response to specific and repeated acts of violence and vandalism, not in response to peaceful protest"

-ABC News' Jessica Gorman and Kevin Shalvey

After Columbia University was cleared of encamped protesters Tuesday night, the school said it its Morningside campus was immediately restricted to students who live there and workers providing essential services.

"Effective immediately, access to the Morningside campus has been limited to students residing in residential buildings on campus (Carman, Furnald, John Jay, Hartley, Wallach, East Campus and Wien) and employees who provide essential services to campus buildings, labs and residential student life (for example, Dining, Public Safety, and building maintenance staff). There is no additional access to the Morningside campus," the notification read.

The university said the restrictions would stay in place "until circumstances allow otherwise."

-ABC News' Victoria Arancio

NYPD officers entered the campus of the City College of New York late Tuesday night.

"As requested by the university, we are currently on campus to assist the university in dispersing those trespassing," NYPD Deputy Commissioner of Operations, Kaz Daughtry, said in a post on X, sharing video of the police moving in.

In a note to the campus community, university president Vince Boudreau, said protests on campus presented "heightened challenges."

"Most importantly, this is not primarily a CCNY demonstration, and perhaps not primarily a CUNY demonstration. The significant inclusion of un-affiliated external individuals means that we don’t have established connections to them," Boudreau's letter read.

He continued: "Specifically, this demonstration has been more contentious and violent than anything we’ve seen on campus before. Today, we distributed a letter to members of the encampment detailing specific examples of threats to the safety of people within and outside the encampment, so that all of them understand the full scope of the activity. We also want all of them, and those of you reading this note, to understand that in no way does our response to this particular and extraordinary threat overwrite our more fundamental commitments to free speech, academic freedom, or the right to peacefully protest that comply with CCNY and CUNY regulations."

Boudreau said the encamped demonstrators were told to take down their encampment and follow CUNY guidelines for "future activities."

The university president also said classes would be remote on Wednesday due to the situation on campus.

-ABC News' Jolie Lash and Victoria Arancio