So, a student cut the hands of the police after they responded to the site of the protest for a broken glass door? Must be. "Police" is the only plural noun in the sentence that could possibly be the antecedant for the plural pronoun "their".
BE VERY CAREFUL OF THE RAMINICATIONS OF ANY RULES, LAWS AND THE POWER OF THOSE CONTROLLING THE PRESS. We learn too low and almost do not see the dangers of political correctness. MOO