Dom welcomes in Officer Mark Dallas, a retired school resource officer from out in Dixon, Illinois, who thwarted a school shooting at a graduation rehearsal a couple years back by shooting and wounding the assailant. Dallas was invited on the show after a new budget was passed within the past few weeks in Pennsylvania that suggests all school districts employ an armed security guard. Dallas takes us through the sad day, and explains why his presence saved many lives, telling how he hopes to help to train incoming resource officers. (Photo by Getty Images)