Thoughts
It was the evening of the Virginia Tech shootings, and I was on the phone with my brother, who teaches at another college in Virginia (ODU). He said "Somebody's going to lose their job over this", and then added, "But I hope not. Hopefully cooler heads will prevail." I agreed -- the campus cops did exactly the right thing under the circumstances. When you come across two shooting victims in a dorm room you start looking for a jealous ex, not a demented mass-murderer.
And as for whether anyone should have seen it coming, or could have prevented it... Doubtful. The only things that might have prevented it would have been teaching young kids not to tease or bully people who are different from them, and a health care system that provides decent mental health care, and a culture that makes it easier for an asocial loner to seek out care than to avoid it. Good luck.