A policeman killed 6 people

A 20 age policeman in Wisconsin , USA , shot a gun at random , killed 6 people and fell in another policeman`s postol . 3 of killed people are high school students . Because one of the victims was a former girlfriend of the policeman , it is said that this incident had happened because their talk about breaking off their relationship was snarled up . I was little shocked to know this news . I think the policeman , whose duty is save people from danger did such killing because his broken heart , is very shameful . Similar incident had happened in Japan recently and a woman was killed by a policeman who stalked her . I think they must know what are their jobs and their duties .