such instances are rare and not prevented by police control. If one wanted to do the same as what was done at any one of the "school shooting tour" schools at a school such as mine with 1 cop, one could quite easily, without even bringing a gun to school. get 3 guys, aproch the cop in his office, tackle his ass, kick him a bunch of times, steal his gun, kill as many as posible before more cops show up. one way to protect people from crazy fucks like "one" is to not have a cop at all. Another way is to have 100 cops with ak-47s. both have the same result