New details emerge in shooting at White House Correspondents' Dinner

Samantha Vinograd, CBS News national security contributor, told "Face the Nation with Margaret Brennan," that the country is facing "the most complex threat environment" in its history. "In this scenario, two things can be true. It can be true that law enforcement and intelligence professionals prepared exhaustively for last night, weeks of planning, intelligence gathering, physical security barriers, officers on site," she said. …