3 dead 144 wounded so far, seriously graphic pictures of blast amputations all over yahoo/google images. The marathon was probably targeted because it's a large high population soft target, stadiums are actually pretty hardened nowadays but a 26 mile long target of public roadways is about as soft as it gets and the finish line is attended by thousands. I'm glad they didn't use a powerful bomb, the aftermath actually looks like they were using low explosives. 3 undetonated devices have been recovered so they will know what type of explosive was used. If they used C4 (this was NOT C4) they will be able to trace it by the marking agent that all C4 is manufactured with by law. I would guess they used flash powder, it's almost as powerful as a high explosive and it's the easiest explosive to manufacture and the two ingredients can be purchased readily. Flash powder has a very bright flash though when it is ignited as the aluminum burns up so probably not flash powder. You can see where the finish line bomb was detonated in the photos, it left a burn on the ground but did almost no damage to the sidewalk so low explosives are the most likely culprit or possibly a very small ammonium nitrate device. The smoke and flame color looked very similar to an ammonium nitrate detonation. I'm guessing they have almost everything figured out by Friday, finding the 3 undetonated devices is a major break in the investigation. It's unlikely 5 devices were planted by a single person which should also make it more likely they get to the bottom of this.