Columbia University cancelled in-person classes on Monday and police arrested several dozen protesters at Yale University as tensions on college campuses across the country continues to grow over the war in the Middle East.

The moves at the two Ivy League schools came hours hours before the Jewish holiday of Passover was set to begin Monday evening.

Police officers arrested about 45 protesters at Yale in Connecticut and charged them with misdemeanor trespassing, said Officer Christian Bruckhart, a spokesperson for New Haven police. All were being released on promises to appear in court, he said.

Last week, police arrested more than 100 pro-Palestinian demonstrators at Columbia in New York who had set up an encampment on the campus.

Columbia President Minouche Shafik said in a note addressed to the school community Monday that she was “deeply saddened” by what was happening on the campus.

“To deescalate the rancor and give us all a chance to consider next steps, I am announcing that all classes will be held virtually on Monday,” Shafik said.

She said faculty and staff should work remotely where possible and that students who didn't live on campus should stay away.

Shafik said there was a terrible conflict raging in the Middle East and she understood that many were experiencing deep moral distress.

“But we cannot have one group dictate terms and attempt to disrupt important milestones like graduation to advance their point of view,” Shafik wrote.

Over the coming days, a working group of deans, university administrators and faculty would try to find a resolution to the crisis, she said.

It wasn't immediately clear from the president's note when in-person classes would resume.

Several students at Columbia and Barnard College said they'd been suspended as a result of last week's protests, including Barnard student Isra Hirsi, who is the daughter of Democratic US Rep. Ilhan Omar.

At Yale, a large group of demonstrators re-gathered after Monday's arrests and blocked a street near campus, said Bruckhart, the police spokesperson. There was no reported violence or injuries.