Medical personnel load an injured person into an ambulance outside Saugus High School in Santa Clarita, Calif., after a student gunman opened fire at the school on Thursday, Nov. 14, 2015. (Rick McClure via AP) SANTA CLARITA, Calif. (AP) — A boy described as bright, quiet and “normal” pulled a gun from his backpack on his 16th birthday and opened fire at his high school before saving the last bullet for himself, authorities said. The shooting that killed two teenagers…