Okay...The bomber/s did not do this because they were mad over a flat tire. This was done in order to inspire terror in the American populace. By definition it is terrorism. The bandy with words is the descriptive that would go in front of the word "terror", but it is terrorism regardless. Also it is textbook terrorism, a large outdoor gathering with lots of participants and cameras to boot.. Doesn't get any better than that for someone intending to induce terror.