Surveillance video released shows a high school principal tackling a gunman who had opened fire in the school in Oklahoma. The moment captured on the school's security camera came after the suspect opened fire at Pauls Valley High School on April 7. The school's principal, Kirk Moore, can be seen sprinting into the school's lobby, then tackles the gunman onto a bench and holds him down. Moore was shot in the leg at some point during the attack, but no students were injured. Police arrested