>> fbi agents are focused on the method cal work of pulling clues from the marathon route what is now a crime scene. the residue of explosion to determine the type of explosive the origin and as well as whether they contained any shrapnel. that will be a critical clue. >> i think it's very clear. i think the fbi is treating it as such this was an act of terrorism. when you see ball bearings. >> let me interrupt you. i am sorry. >> we still don't not know who did this or why. people shouldn't jump to conclusions. i am con if i p dent boss tonians will come together and move forward as a proud city. the day after the marathon bombing zoe har tsarnaev was