Before the cop could get off a shot , my friend lifted a rifle and fired a round right into the gas tank . The motorcycle burst into a fireball , of course - really great action movie stuff here , folks . Then my friend looked at me with a slight smile , an expression of deep care and affection that said , " I ' m here for you , Trevor .

Question: Why did the motorcycle blow up ?
Answer: A truck hit the gas tank .The cop blew it up .The cop fired into it .The narrator 's friend shot it .