Barbara Riggs Profile: Barbara Riggs Events (2) (9:37 a.m.) September 11, 2001: Counterterrorism ‘Tsar’ Clarke Learns of Aircraft Approaching White House 2001-09-11 (9:45 a.m.) September 11, 2001: White House Evacuated after Secret Service Learns of Plane en Route to Washington 2001-09-11