Columbia University requested help from the New York City Police Department to clear pro-Palestinian demonstrators out of the campus library Wednesday evening.
"Due to the number of individuals participating in the disruption inside and outside of the building, a large group of people attempting to force their way into Butler Library creating a safety hazard, and what we believe to be the significant presence of individuals not affiliated with the University, Columbia has taken the necessary step of requesting the presence of NYPD to assist in securing the building and the safety of our community," Acting University President Claire Shipman said, in part, in a statement.
She added, "Requesting the presence of the NYPD is not the outcome we wanted, but it was absolutely necessary to secure the safety of our community."
NYPD officers were seen removing at least 20 protesters from the library.
Video shows protesters flooding into Columbia's Butler LibraryVideo shows protesters storming Butler Library earlier in the afternoon, occupying one of the building's rooms and vandalizing property.
A university spokesperson said the school's public safety team quickly responded. According to the university, protesters were asked to show their IDs and disperse. The university says protesters' identification "will be recorded."
As of early evening, no protesters had chosen to identify themselves and leave, the university said. Protesters were told failure to comply may result in arrests, the school added.
Individuals who were in the library but not involved in the protest were allowed to leave, the university said.
At least three people were seen being taken into custody by public safety.
First responders were seen taking someone out of the library on a stretcher, and a fire alarm was heard going off inside.
Meanwhile, video from Chopper 2 shows a large crowd of protesters gathering outside the library, apparently trying to push their way inside.
Shipman said two Columbia public safety officers were injured "during a crowd surge when individuals attempted to force their way into the building and into Room 301."
Pro-Palestinian demonstrations at Columbia UniversityIt was all happening while the school is in a pre-final exams reading week.
"While this is isolated to one room in the library, it is completely unacceptable that some individuals are choosing to disrupt academic activities as our students are studying and preparing for final exams. These disruptions of our campus and academic activities will not be tolerated. Individuals found to be in violation of University Rules and policies will face disciplinary consequences. We ask our community members to please avoid the immediate area near Butler Library in the near term," a university spokesperson said, in part.
Many protesters were seen wearing masks. Columbia announced a mask ban earlier this year as part of the new policies enacted under the Trump administration's demands.
Columbia University has been in the crosshairs of the Trump administration in the wake of last year's pro-Palestinian campus protests, threatening to withhold hundreds of millions of dollars in federal funding if certain changes weren't implemented at the school. Two prominent student activists were also arrested by federal immigration authorities, Mahmoud Khalil and Mohsen Mahdawi.
Stay with CBS News New York for the latest on this developing story.
More from CBS News
Ali Bauman