NYPD enter occupied Columbia University building

STORY: A long line of helmeted police officers in tactical gear were seen climbing into the building through a second-story window, using a vehicle with a ladder to gain access to the upper floor of the Hamilton Hall, an academic building that protesters had broke into and seized control of in the early morning hours of Tuesday.

The occupation began overnight when protesters broke windows, stormed inside and unfurled a banner reading "Hind's Hall," symbolically renaming the building for a 6-year-old Palestinian child killed in Gaza by the Israeli military. Columbia University officials earlier on Tuesday threatened academic expulsion of the students who seized Hamilton Hall.

New York Police Department officials had stressed before Tuesday night's sweep that officers would refrain from entering the campus unless Columbia administrators invited their presence, as they did on April 18, when NYPD officers removed an earlier encampment. More than 100 arrests were made at that time, stirring an outcry by many students and staff.