they talked to one of the runners that was in the area who just returned from iraq and he said that as soon as he heard it and saw the smoke it reminded him of an i.e.d..

they also said that they had police with bomb sniffing dogs near the areas where the runners were coming through, so whoever did this was able to sneak by the dogs without being detected, thats how deteremined they were.

as far as the other bombs being detonated, our enemies overseas think nothing of killing themselves with bombs strapped to themselves while killing us, who's to say that they could'nt detonate those other bombs because they could'nt get far away enough from one of the ones that exploded. there was 2 people killed ( the 8 year old excluded ) it could have been one of those 2.