150 Gather In N. Mpls. For Gun Violence Prevention SummitMary Johnson's son was murdered 20 years ago. She has since forgiven the man who killed him, but still feels compelled to work to stop the killing. "Our youth should not be able to walk out of their door, and walk down the block and get a gun," Johnson said. The summit included police officers, pastors and citizens - working to end gun violence. Among the attendees was Leroy Duncan of Protect Minnesota.