How are the Police to blame ?
I have only limited information on this,so something else may come out to explain why people are blaming the police.
I don't understand how the Police should be expected to look a double murder and state with any certainty that the guy will go on a rampage against other students. After all if they had announced it at the time and had been incorrect they catch just as much crap for 'emotional distress' or some other claim.
Undeniably this is a tragedy, which sadly America is unlikley to learn from, but blame the muderer and whoever allowed him to get the gun not the Police