Dozens of pro-Palestinian protesters at Columbia University were arrested Thursday afternoon and an on-campus tent encampment was removed after the school's president gave the New York Police Department the green light to clear the protesters.

Columbia President Nemat "Minouche" Shafik announced in a letter to the Columbia community Thursday that she has authorized the New York Police Department to clear demonstrators from campus, writing, "This morning, I had to make a decision that I hoped would never be necessary."

"I regret that all of these attempts to resolve the situation were rejected by the students involved. As a result, NYPD officers are now on campus and the process of clearing the encampment is underway," Shafik said.

She added, "I have always said that the safety of our community was my top priority and that we needed to preserve an environment where everyone could learn in a supportive context."

Columbia also released a letter to the NYPD authorizing the action.