Police start arresting protesters at Columbia University building, start clearing occupied Hamilton Hall

New York: Hundreds of police officers in riot gear began arresting pro-Palestinian demonstrators at Columbia University on Tuesday night, about 20 hours after protesters had seized a campus building. The occupation further escalated the crisis that has consumed the school and ignited student activism on dozens of campuses nationwide.

The officers climbed a ladder and broke a window on the second floor to enter the occupied building, Hamilton Hall, then led protesters in zip ties onto law enforcement buses parked near campus.

The action came nearly two weeks after the police arrested more than 100 protesters who had set up tents on the upper Manhattan campus. The police action outraged many faculty members and students, who almost immediately pitched new tents. Since then, the encampment has grown to be larger than the original.

After demonstrators seized Hamilton Hall, a building with a history of student takeovers, the university closed the campus to everyone but students who live there, as well as employees who provide essential services, and said it would move to expel any students who had occupied the building.

What to know about Columbia:

— Many protesters left Columbia’s encampment Monday as the university’s deadline for doing so neared. But several dozen protesters and about 100 tents remained Tuesday.

— The student organization behind the encampment, Columbia University Apartheid Divest, said that “an autonomous group” had seized Hamilton Hall, a building with a history of student takeovers, and would stay until the university conceded to CUAD’s demands, which include divestment from companies doing business in Israel.

— Columbia administrators closed the Manhattan campus Tuesday to everyone but students who live in dorms there and employees who provide essential services.

What’s happening elsewhere:

— In Oregon, demonstrators who took over a library at Portland State overnight used wood pallets and other supplies to erect fortifications around the building’s entrance. University officials Tuesday urged them to leave the library, which was covered in pro-Palestinian messages, and requested help from the police.

— Police officers moved into an encampment at UNC Chapel Hill early Tuesday and arrested about 30 people, school officials said. Protesters returned later in the day, mowing down a barrier to rejoin the encampment and replacing an American flag at the center of campus with a Palestinian one.

— At Virginia Commonwealth University in Richmond, officers broke up a protest Monday night with riot gear and pepper spray, administrators said, after protesters “threw objects and used chemical spray on officers.” Thirteen people, including six students, were charged with unlawful assembly and trespassing.

— More than 1,000 protesters have been taken into custody on US campuses since the original roundup at Columbia on April 18, according to a tally by The New York Times.