The turmoil at Columbia University ramped up on Monday as simmering tensions on campus halted in-person classes and officials scrambled to ease security fears.

The Ivy League school has become the epicenter of unrest on US college campuses, turmoil that spread to Yale University, where dozens of pro-Palestinian protesters were arrested Monday.

Security concerns are so significant that Columbia officials decided to make all classes virtual on Monday just as Passover begins. In a clear sign of the spiraling crisis, Columbia President Minouche Shafik announced the extraordinary step in a statement posted shortly after 1 am ET, citing a desire to “deescalate the rancor and give us all a chance to consider next steps.”

As the New York Police Department has built up a “large presence” around Columbia, New York Governor Kathy Hochul visited the campus to address security concerns.

“Students are scared,” Hochul said in a video posted on X. “They are afraid to walk on campus. They don’t deserve that.”

Shafik now faces enormous pressure to get the situation under control, with some calling for her to resign.

Billionaire Robert Kraft, the owner of the New England Patriots and a prominent Columbia graduate, called for school officials to immediately end the protests and suggested he is withholding donations to the university because he’s “no longer confident that Columbia can protect its students and staff.”

“The school I love so much – the one that welcomed me and provided me with so much opportunity – is no longer an institution I recognize,” Kraft, founder of the Foundation to Combat Antisemitism, said in a statement on X, formerly known as Twitter. “I am not comfortable supporting the university until corrective action is taken.”

Columbia spokesperson Samantha Slater responded to Kraft by telling CNN in a statement that the university is “grateful to Mr. Kraft for his years of generosity and service to Columbia.”

“This is a time of crisis for many members of our community and we are focused on providing the support they need while keeping our campus safe,” the Columbia spokesperson said.

Protests and counter protests continue

As Columbia students moved to virtual learning, scores of protestors were camped out on the university’s West Lawn Monday morning opposite the lawn where the original encampment took place.

More than a dozen tents were pitched and tables were stocked with supplies of clothes and food. Signs along the perimeter include ones reading, “End the siege on Gaza now” and “Welcome to the People’s University of Palestine.”

Meanwhile, pro-Israel protestors gathered outside the Columbia gates Monday morning, with some waving Israeli and American flags.

“This is happening at every US university. Jews are not safe anywhere on college campuses,” Shai Davidai, a Jewish Columbia Business School assistant professor, told the group of pro-Israel protestors.

Columbia officials said last week that Davidai is under investigation for harassment. Davidai told CNN he has never spoken against students by name, only “pro-Hamas” students organizations and professors.

At Yale University, at least 45 people had been arrested — including some students – after police blocked off entrances during response to a protest at Hewitt Quadrangle & Beinecke Plaza, the school’s independent college newspaper, The Yale Daily News reported Monday morning.

“Cops have gathered at Beinecke Plaza, where pro-Palestine protesters urging Yale to divest from military weapons manufacturers set up tents overnight – the third night of their ongoing encampment,” the Yale Daily News said.

Journalists from the Yale Daily News were also threatened with arrest if they did not move from the plaza, according to reports.

CNN has reached out to Yale University administration, the Yale Police Department and the New Haven Police Department in Connecticut for more information.

Tensions at many universities have been high ever since the October 7 terror attack on Israel by Hamas. However, the situation at Columbia escalated in recent days after university officials testified before Congress last week about antisemitism on campus and pro-Palestinian protests on and near campus surged.

At Columbia, “During the coming days, a working group of Deans, university administrators and faculty members will try to bring this crisis to a resolution. That includes continuing discussions with the student protestors and identifying actions we can take as a community to enable us to peacefully complete the term and return to respectful engagement with each other,” the president said in her Monday statement.

As the situation has unfolded, Shafik has faced new calls for her resignation, and a rabbi linked to the university even urged Jewish students to stay home due to concerns about their safety as Passover, a major Jewish holiday, is set to begin Monday evening.

The safety of Columbia’s community is “our number one priority,” a university spokesperson told CNN in a statement Sunday.

“We are acting on concerns we are hearing from our Jewish students and are providing additional support and resources to ensure that our community remains safe,” the statement added.

The White House, New York Gov. Kathy Hochul and New York City Mayor Eric Adams all weighed in over the weekend, denouncing calls for violence against Jews.

Adams said he was “horrified and disgusted with the antisemitism spewed at and around” Columbia and said the New York Police Department “will not hesitate to arrest anyone” found to be breaking the law.

Rabbi Elie Buechler, a rabbi associated with Columbia University’s Orthodox Union Jewish Learning Initiative on Campus, confirmed to CNN’s Jake Tapper on Sunday he sent a WhatsApp message to a group of about 300 mostly Orthodox Jewish students “strongly” recommending they return home and remain there.

In his message, Buechler wrote recent events at the university “have made it clear that Columbia University’s Public Safety and the NYPD cannot guarantee Jewish students’ safety.”

“It deeply pains me to say that I would strongly recommend you return home as soon as possible and remain home until the reality in and around campus has dramatically improved,” the message reads.

The campus Hillel said in a Sunday post on X they “do not believe that Jewish students should leave” the campus, but that the university and City of New York must act to protect students from harassment.

Student: I’m ‘terrified, angry, upset’

“If I had my child at Columbia, I also would tell them to go home,” Hagar Chemali, an adjunct associate professor of International and Public Affairs at the university, told CNN Monday. “It’s not just because of the tension on campus, it’s also because those protests on campus have invited extremists outside.”

Organizers of the campus protest – Columbia University Apartheid Divest and Columbia Students for Justice in Palestine – said in a statement, “We have been peaceful,” and distanced themselves from non-student protestors who have gathered outside the campus, calling them “inflammatory individuals who do not represent us.”

“We firmly reject any form of hate or bigotry and stand vigilant against non-students attempting to disrupt the solidarity being forged among students – Palestinian, Muslim, Arab, Jewish, Black and pro-Palestinian classmates and colleagues who represent the full diversity of our country,” the activists’ statement continued.

Columbia student, Noah Lederman, told CNN he was “terrified, angry, upset, and horrified that the university failed to take action.” Lederman said he had been accosted in early February and had asked the university for remote learning options. “What’s happening on campus is blatantly antisemitic,” he added.

“Columbia students organizing in solidarity with Palestine – including Jewish students – have faced harassment, doxxing, and now arrest by the NYPD. These are the main threats to the safety of Jewish Columbia students,” Jonathan Ben-Menachem, a Ph.D. student, told CNN.

“On the other hand, student protesters have led interfaith joint prayers for several days now, and Passover Seder will be held at the Gaza Solidarity Encampment tomorrow,” he went on. “Saying that student protesters are a threat to Jewish students is a dangerous smear.”

Demonstrations are also taking place at other campuses. Pro-Palestinian students at Emerson College and the Massachusetts Institute of Technology set up protest encampments as an act of solidarity with students at Columbia University, according to The Boston Globe. Solidarity rallies have also taken place at Yale, Harvard, the University of North Carolina, and Boston University.

Crisis is a test for Columbia’s new president

The crisis at Columbia amounts to a massive test for Shafik, who took the helm of the university less than a year ago.

Rep. Elise Stefanik, the New York Republican and frequent critic of Ivy League schools, called for Shafik to immediately step down.

“It is crystal clear that Columbia University – previously a beacon of academic excellence founded by Alexander Hamilton – needs new leadership,” Stefanik said in a statement on Sunday.

Following a disastrous hearing on campus antisemitism before Congress in December, the presidents of Harvard University and the University of Pennsylvania came under enormous pressure and both resigned.

Shafik testified to the House Education Committee on the same subject last Wednesday, and the protests on campus have escalated in the days since, prompting Republican committee chair Rep. Virginia Foxx to warn university leaders of consequences if they do not rein in the protests.

“Columbia’s continued failure to restore order and safety promptly to campus constitutes a major breach of the University’s Title VI obligations, upon which federal financial assistance is contingent, and which must immediately be rectified,” Foxx wrote in a letter.

As Passover begins Monday, Jewish student organizations have increased security for their upcoming events and services.

Police will be present at the Kraft Center, a Jewish cultural center shared by Columbia and Barnard College, throughout Passover, and students will be able to get walking escorts to and from the building starting Monday, according to an email from Brian Cohen, the center’s executive director.

Chabad, another Jewish organization at the university, said they are still planning on hosting Passover celebrations but have hired additional security to protect students.

CNN’s Elizabeth Wolfe, Paradise Afshar, Caroll Alvarado, Shimon Prokupecz and John Towfighi contributed to this report.