 It's the leading cause of death in children and teens in America, and there's now a warning about how destructive gun violence can be. Surgeon General Dr. Vivek Murthy calling gun violence a public health crisis and a new advisory. Murthy outlining the lasting effects gun deaths are having on communities nationwide. Murthy talks with ABC's Phil Lipoff on the problem, how it's affecting all of us, and what can be done. What concerns you the most here?