A law enforcement official tells CBS News that the two bombs that exploded in Boston were made to look like discarded property. It is still unknown if one or both bombs were in garbage cans. One may have been on the sidewalk.
The bombs are described as "low explosive, but with "anti-personnel" packing. This is consistent with doctors reporting shrapnel pulled from victims. This law enforcement official tells us that there were apparently things like bb's, ball bearings and nails in the bombs.
While the explosions were fairly large, the bombs were made of "low explosives." Right now bomb experts do not think that plastic explosives were involved.