Clancy had that one pegged years ago in 'Sum of all Fears'. (Insert standard 'The book was way better than the movie' clause here.) I wouldn't be surprised to see Disneyland, a sporting event, a concert, or anything they deem 'inappropriatly fun' get waxed.
Huge gatherings of people having fun attract terrorists like flies. (I've heard that Jerry Garcia was actually assassinated by Islamic terrorists after they went to one of his concerts to see 'hundreds of hippies get stoned'. Apparently it wasn't the kind of stoning they were hoping to see, and they offed him out of bitter disappointment.)
If you really give that tale any credance at all, then I have a wonderful bridge for sale...
Impossible. When they did the autopsy the doctors found absolutely no blood in his drug veins. :-P