White House lockdown lifted, Obama leaves

A security lockdown at the White House triggered by a loud bang just as President Barack Obama was due to leave was caused by a food vendor cart catching fire on a nearby street, the Secret Service said on Saturday. The security alert happened just moments before Obama and his family had been due to board a helicopter from the presidential mansion's South Lawn for Andrews Air Force Base. Secret Service spokesman Brian Leary said the fire had now been contained and that a vehicle near the Wh