went off. they're analyzing the pieces now. they will try to get what you might call a signature of the twice to see if it's similar to other devices here or oversees, but their initial take on looki the buildings, injuries, pictures of the explosion, they zwrieb the devices as thankfully crude with less power than might have been contained in something of that size. >> on that point, on the nature of these explosives, obviously those of us who are watching this footage over and over again of a bomb going off in a civilian environment, it looks huge, but can we get a perspective on the size and power of the bomb? how we might compare to to those in a war zone, ieds or military