I'm sure you include the poor man who thought this was an answer...what a testament that his note said something about "now I'll be famous" and by god, the media granted him his wish.
Nothing to convince the next person that won't remain the case if they want to go out in a blaze of glory and be "infamous."
Lord, in your mercy, help heal our wounded friends and neighbors that such tragic events can become a thing of the past. Until then, Lord, please be with those lost in such senseless violence (isn't it all senseless?) and bring them your Holy Peace. For those that don't know you, Lord, use this time to bring them to you through us and our witness. Amen.