what they're looking for is nip right in that area and left just before the explosions, as opposed to the chaos that happens just after the explosions. >> and john, are they saying, and brian maybe you heard this, as well. have they said publicly if they know exactly where the devices were? you know, in a garbage can, a mailbox or -- do they know? >> i was told by one source earlier the suspicion, and i want to emphasize the suspicion. they will look through the debris. and the bomb experts can figure out if there's a mailbox been broken up or a garbage can, they can look for explosive materials inside it. i was told earlier they suspect a mailbox or garbage pale but did not have definitive information. >> what we are hearing from the nature of the injuries is they believe it was a device close to the ground. >> and not a sophisticated device.