Hundreds of police officers in riot gear marched onto the campus of Columbia University in Upper Manhattan late Tuesday, where protesters had occupied a campus building, as clashes over the war in Gaza continued to escalate at American universities.

Around dusk, police officers pepper sprayed protesters to prevent the takeover of a building on another Manhattan campus, the City College of New York, and pepper spray was used on demonstrators elsewhere around the country this week, including at campuses in Richmond, Va., and Austin, Texas.