Why Boston's hospitals were ready

The bombs at the Boston Marathon were designed to maim and kill, and they did. Three people died within the first moments of the blast. More than a hundred and seventy people were injured. They had their limbs blown off, vital arteries severed, bones fractured, flesh torn open by shrapnel or scorched by the blasts' heat. Yet it now appears that every one of the wounded alive when rescuers reached them will survive. Medically speaking, this is no small accomplishment. We've seen bombs like this in the battlefields of the Middle East, but rarely in cities like Boston.