BEND, Ore. — Kaylub Giamanco was driving past his daughters’ elementary school on Wednesday afternoon when he saw a teenager shooting at a pickup truck. Within minutes, the 36-year-old carpenter had followed the gunman inside Silver Rail Elementary School and shot him dead in a classroom. Police say a teacher was struggling with the gunman for his shotgun at the time. Authorities say the October 15 attack killed three boys, ages 5, 8 and 11, and 25-year-old teacher Megan Lamb