perhaps this is part of another incident, maybe it was a description of a vehicle, a driver, able to start matching things. they've been going through video footage and the like. but a lot of work still need to be done to determine exactly how this happened. it may well have not been intentional. he did pass a lot of people he could have struck, if the intent was to cause that cairn original, he could have done it a lot earlier than the actual crash site. >> julia, you worked at the department of homeland security. i don't want to give the impression you or anyone can protect against every threat every time but we know in the past vehicles have been used intentionally and again the circumstances here don't seem to look that way at least right now. as you look at the setup, were there any missed opportunities to provide better security for the parade route or is this just a difficult one to handle? >> it's a difficult one to handle. the more security you put on events like this, the local