After the initial invasion of a university building where three school officials are taken hostage for 24 hours, on April 24, additional buildings are occupied by a growing mass of rebellious students, estimated to be 700 to 1,000 strong and extending beyond the original core of SDS (whose Columbia chapter consist of about 150 members) and the Students Afro-American Society. Student protesters ransack the university president’s office and go on to occupy a total of five buildings. On the sixth day of the disorders, more that 1,000 policemen enter the campus and clear the buildings in a violent and chaotic student-police encounter. Classes at Columbia come to a virtual standstill for the rest of the academic year.