 And our hearts go out to the victims of this heinous act. An attendee was also killed. CBS News national security contributor Samantha Vinograd says it isn't easy to defend against lone wolf attacks. The intelligence and law enforcement community has been warning for months, if not years, about the threat of what we call lone actors or small groups of individuals. Basically, individuals who are mobilized and radicalized by themselves who really present an intelligence challenge. CBS News special report. I'm Christopher Cruz.