The overwhelming feeling for many, including myself, is a need to know why. Not because it would make sense or make it any better. Just because having so much suffering and not knowing why is just so empty.
The idea of a person causing carnage for the sake of carnage, with no other motivation, is really a difficult concept to deal with. 911 was horrible, but there was a reason for the target. There was a way to compartmentalize it and try to move forward. Having no reason - not even a crazy reason - makes one feel like the value of human life is as close to zero as it has ever been.
There was a group of people running in the marathon from Newtown, CT. "26 miles for 26 lives" I think they called themselves. How about that ...
Then today we can't even pass a watered down gun bill. How many ways can we sh1t on victims of violence?
I'm sure the NRA will be saying that if every runner had carried a gun this would never have happened.