In a message to the campus community Monday, Massachusetts Institute of Technology President Sally Kornbluth gave students until 2:30 p.m. to leave the encampment on campus.

However, protesters remained in the area until after the deadline. It's unclear if police will move in and make arrests.

"In short, this prolonged use of MIT property as a venue for protest, without permission, especially on an issue with such sharp disagreement, is no longer safely sustainable," Kornbluth said.

The encampment on MIT’s campus, on the Kresge lawn, has been ongoing for more than two weeks, according to Kornbluth.

Police moved in on an encampment at the University of California, San Diego early Monday morning, dismantling it and arresting 64 people, according to authorities.

There were 40 students among those arrested, with officials saying they "have been or will be placed under immediate interim suspension."

All classes were moved to remote learning and nonessential personnel were asked to remain home.

Several dozen protesters were detained on UCLA’s campus Monday morning, according to Los Angeles ABC station KABC.

University officials said all classes would be held remotely Monday “due to ongoing disruptions,” and police would be stationed around campus.

Harvard University students who continue to take part in the pro-Palestinian protest encampment at the school will be “referred for involuntary leave,” the university’s interim president, Alan M. Garber, said Monday.

In a letter to the student body, Garber called on protesters “to end the occupation of Harvard Yard,” arguing that the encampment “favors the voices of a few over the rights of many who have experienced disruption in how they learn and work at a critical time of the semester.”

Students placed on involuntary leave “may not be able to sit for exams, may not continue to reside in Harvard housing, and must cease to be present on campus until reinstated,” he wrote.

“As an academic institution, we do not shy away from hard and important questions,” Garber wrote. “There are many ways for our community to engage constructively in reasoned discussion of complex issues, but initiating these difficult and crucial conversations does not require, or justify, interfering with the educational environment and Harvard’s academic mission.”

-ABC News' Julia Reinstein

In a letter authorizing the NYPD to enter the Columbia University campus and break up the protest, the school detailed the backstory on its recent talks with those in the encampments and the takeover Tuesday night of Hamilton Hall.

According to the letter, from Columbia President Minouche Shafik, an individual "hid in the building" at Hamilton Hall until it was closed and let others in. The group's purpose was "occupying the building," the letter read.

Two security guards were inside the building at the time, and the university said in the letter to the NYPD they were able to "secure their release."

"We believe that while the group who broke into the building includes students, it is led by individuals who are not affiliated with the University," the letter read. "The individuals who have occupied Hamilton Hall have vandalized University property and are trespassing."
Addressing the encampment on the school's Morningside campus, the university told police discussions had been carried out with group representatives, but on Sunday, they "reached an impasse."

At that time, the university says it told the group they did not have permission to "occupy spaces on campus" and were "in violation" of school rules and policies.
On Monday morning, the protesters were told they would be suspended if they didn't disperse by Monday at 2 p.m. ET.

The university said in its Tuesday night NYPD letter that those in the encampment were "suspended" and "not authorized to be on University property and are trespassing."

The university said it believed the actions of those in the protest were escalating. "These activities have become a magnet for protesters outside our gates which creates significant risk to our campus and disrupts the ability of the University to continue normal operations," the letter read.

Columbia's president concluded the letter by asking the NYPD to "help to clear all individuals from Hamilton Hall and all campus encampments."

She further asked police to have a campus presence through May 17 -- graduation is May 15 -- "to maintain order and ensure encampments are not reestablished."

Police moved onto the Columbia University campus a little before 9 p.m. ET and began making arrests.

The NYPD also used a vehicle with an extendable roof ramp to help officers breach Hamilton Hall from an upper floor. From there, the police cleared the building.

The campus encampment and hall were cleared before 11:30 p.m.

-ABC News' Jolie Lash, Aaron Katersky and Joshua Hoyos