answered. was this a freak accidental explosion of some kind? was it intentional? >> it is quickly determined that the explosion at the federal building was caused by a truck bomb. >> there are certain things you can look for, particularly in the case of a large vehicle bomb. there was roughly a 32 foot crater in the street. it appeared to be just about dead center of the block. >> then investigators get their first big break. >> he came from the truck bomb and has landed around 200 yards from the bomb site. >> i heard something coming through the air, and i looked up. you see this big object coming straight towards us, and when it hit the car, it knocked it back to these other sets of doors back here, and i look in front of my car, and there was an axle in there, and i told my wife, it's a car bomb. >> early indications are the bomb was a half ton homemade bomb that was made of common fertilizer and fuel oil. >> fortunately, the axle housing contains the truck's confidential vehicle identification number. >> using that number we are able to trace the people sxifts identify it as a ford motor product that had been made for