FB is a powerful tool: plenty of images just seconds old. Plenty of on-the-scene reports. One FB friend's son was there and reported in ok and leaving the scene. For all its negatives, FB is an amazing technology.
Two photos that were shared with us. Very powerful!
And a final photo that, while its been around for a while, its meaning is all too clear now. (See the post we were writing when the Boston bombs went off)
UPDATED 4.16 7:45am: