this is a significant change from the vehicular and stabbing ataxia seen in london throughout the yearve all been crude except for the suicide bombing. of course up until now, this was an attempt i think, to really try and take out a couple dozen people. it was a crude device. the good news here is that investigators can now take a look the parts, they can try to determine where the parts came from. they can try to determine exactly how the seller individuals learn how to assemble the device. and of course they have all of the cctv and other evidence out there where they can go after and track these people or this person. >> the terror threat level in the uk has been raised to critical. it is the highest level there is meaning that there is an attack that is imminent. this happened only four times since 2006 that they have this level. so how should people living in the uk be prepared at this point? >> well, look, i think it is inadvisable for people to stay home and not want to go outside. the police and authorities are doing everything they can right now to track what they believe is