New York City police have entered the Columbia University en masse and are arresting students. The NYPD told the BBC officers have entered Hamilton Hall, an academic building recently occupied by pro-Palestinian protesters. The activists had taken over the Hamilton Hall building nearly 24 hours earlier amid two weeks of campus protests over the Israel-Gaza war. The police were authorised to go in by university authorities, after student demonstrators defied a deadline to disperse. Subscribe here: http://bit.ly/1rbfUog For more news, analysis and features visit: www.bbc.com/news #BBCNews