Just to put it all in context: at least 55. and perhaps as many as 60, people died from bombings in Iraq yesterday, and in Syria, at least 15 (not counting those who died of shelling, aerial bombardment, etc.)
This is in no way intended to denigrate, disrespect, or diminish the tragedy of those who died in Boston. Every person's death diminishes us all. But we are all worth remembering. It's not a competition: journalists used to joke about "Mexican bus equations" (cynically, one dead American roughly equals 100 dead Mexicans in a bus accident, the latter itself a journalistic cliche).
Of course the US media will cover Boston first; Iraq and Syria are both old news and recurring carnage. But no man is an island, but wherever and whenever men and women die at the hands of their fellow humans, it is an assault upon us all.