Rabbi Edwin Friedman, calls it. While I don't kid myself for a moment that I am such for you, I like to think that there's a call for the same in cyberspace, if not at the moment confusing times happen then at the moment you find this.
There is truth to the criticism that people of the US only pay attention to the events that affect people like us and particularly when it happens within our borders. The explosions in Boston, in which only ("only:" how odd is it that we've come to a place when we talk of death in terms of "only"?) two people have died--admittedly, horrifically, one of them an 8 year old boy--lend proof to that. The fact we need to be reminded people in Iraq and Afghanistan, many more people, were killed on the same day need not be a condemnation; we could wish that everyone could be in the position to take notice only of local deaths. That we see such events, as David Sirota writes, as "normal" may actually be beneficial to our identification with the world and with others.
But the fact remains that these things hurt. And they should. We should cry when 8 year old boys and girls are blown apart, when adults who are celebrating a personal or a communal triumph are hit with shrapnel, when someone's hate and anger and fear, because those are the causes of indeterminate killing no matter who the perpetrators are, blows holes in the fabric of our community. We ought to rend our garments and wail and beat our breasts and pound our heads into the dirt. This is the correct human response to human loss.
We don't know who is responsible and may not for some time. We may never know, which is probably the most frightening prospect. It doesn't matter, in the long run; in the long run, as John Maynard Keynes reminds us, we are all dead. How we got that way isn't nearly as relevant.
What is relevant is how we respond to the deaths and injuries of others. We mourn. We keen. We hug our children and our mates and our friends and strangers closer to us for warmth and safety. We help one another in the best ways we know how. We are the nonanxious presence in the presence of anxiety.