Why Did I Feel So Attracted To Onee Of My Guy friends?

Ok Well , I know I am youung & youh guys are gnna saay oh live yor life this & thaat. So Today in second lunch I saw one of my guy friends talking to his other guy friends & wehn I saw him face I go to myself "dang he looks hotter" like I had a crazy imagination I was kissing him like alot. & i been feeling attracted to him for the past few days, & i dont know why. Like in homeroom we stare at each other smiling he told me once he liked me but then he said he didnt like nobody. & well last time in science cl we kept staring at each other for like 2 minutes smiling...why am I soo attracted to him? & why are my hormones going crazy? i am only 13 n he 13 too.