Gun-free zones are invitations to mass murder, gun-rights advocates argued after a lone gunman's shooting rampage at the Sandy Hook elementary school in Newtown, Connecticut, Friday left 20 children and six adults dead. John Lott, author of the controversial 1999 bestseller More Guns, Less Crime, said in an interview with Newsmax.com Saturday it is no coincidence that mass shootings with multiple victims occur repeatedly in designated gun-free zones such as schools, shopping malls, and movie theaters. "The problem is, whether it is the Portland [Oregon] shooting earlier this week, or the Connecticut shooting Friday, or the Sikh temple attack in...