Columbia University has threatened student protesters with "clear consequences" after protesters occupied a building in an escalating standoff. Students defied a 2 p.m. deadline to disperse Monday.

Students occupying the building face expulsion, the university warned.

"We made it very clear yesterday that the work of the University cannot be endlessly interrupted by protesters who violate the rules. Continuing to do so will be met with clear consequences. Protesters have chosen to escalate to an untenable situation—vandalizing property, breaking doors and windows, and blockading entrances—and we are following through with the consequences we outlined yesterday," Columbia said in a statement.

Students who did not commit to the terms Columbia's proposed agreement to vacate the encampment by 2 p.m. Monday have been suspended.

"Those students will be restricted from all academic and recreational spaces and may only access their individual residence. Seniors will be ineligible to graduate," Columbia said.

"This is about responding to the actions of the protesters, not their cause," Columbia said.

Columbia University said it has limited access to its Morningside campus except to students residing in seven residential buildings, labs and employees who provide essential services.

The school has also limited access into and out of the building to one gate, closing all other campus entry points.

The restrictions will remain in place "until circumstances allow otherwise," Columbia said.

New York Police Department officers said they would not enter the property unless Columbia requests it, or there is an imminent threat.

Virginia Tech said it has cleared an encampment on campus and arrested 82 protesters for trespassing, after refusing to comply with university policies.

"Virginia Tech strongly supports free speech, even when the content of that speech may be disagreeable to some. However, those rights do not extend beyond the point where they interfere with the rights of others, violate our policies, the Code of Virginia, or federal laws and/or create a threat to safety for others," Virginia Tech President Tim Sands said in a statement.

Meanwhile, Virginia Tech Muslim Student Association said in a letter the 91 students faculty and staff were arrested for peacefully protesting.

"As we reach the end of the semester, 7 months after Oct. 7, we are finding our voices still unheard. We are waiting for your support of us and Palestine," the Virginia Tech MSA said in a statement.

-ABC News' Nadine El-Bawab and Kerem Inal

California State Polytechnic University, Humboldt said it has cleared two campus buildings that had been occupied by protesters for over a week and arrested 25 people.

"Those arrested faced a range of different charges depending on individual circumstances including unlawful assembly, vandalism, conspiracy, assault of police officers, and others. In addition, students could face discipline for conduct violations while any University employees arrested could face disciplinary action," Cal Poly said in a statement.

The university called the occupation of the two buildings "criminal activity" and said there were "serious concerns it would spread even further on campus."

"This morning’s enforcement action was determined to be necessary to restore order and to address the lawlessness and dangerous conditions that had developed. What was occurring was not free expression or a protest," the university said in a statement.

The campus will remain closed until May 10.

University of California President Michael V. Drake addressed the ongoing protests at UCLA that "turned violent" overnight, announcing in a statement on Wednesday an "independent external review" has been ordered.

The university summoned mutual aid from LAPD officers to "restore control" to the protest, according to Drake, who noted, there were 15 injuries, including one hospitalization, that stemmed from the protest.

"My office has requested a detailed accounting from the campus about what transpired in the early morning hours today," Drake said.

"But some confusion remains, therefore we are also ordering an independent external review of both UCLA’s planning and actions, and the effectiveness of the mutual aid response," Drake said.

UCLA's own chancellor, Gene D. Block, also promised an investigation.

"We are still gathering information about the attack on the encampment last night, and I can assure you that we will conduct a thorough investigation that may lead to arrests, expulsions and dismissals," Block told the campus community in a note Wednesday afternoon.

Block, in his note, said it was "a group of instigators" who came to Royce Quad to "forcefully attack the encampment that has been established there to advocate for Palestinian rights."

He called the overnight violence "utterly unacceptable."

"However one feels about the encampment, this attack on our students, faculty and community members was utterly unacceptable. It has shaken our campus to its core and — adding to other abhorrent incidents that we have witnessed and that have circulated on social media over the past several days — further damaged our community’s sense of security," his letter read.