Workers evacuating City Hall and other b

LOS ANGELES, UNITED STATES: Workers evacuating City Hall and other buildings in the downtown Civic Center area as part the city's first ever multi-building evacuation exercise walk north to a designated safe zone, 09 September 2004 in Los Angeles. The unprecedented exercise involves the simultaneous evacuation of some 20,000 people from City Hall, police headquarters and several other area buildings in response to simulated report of an incoming plane identified as a terrorist threat targetting the Civic Center area. L.A. Mayor Jim Hahn said that the city is preparing for unforseen incidents as the third anniversary of the 11 September attacks on America approaches. AFP PHOTO / Robyn BECK (Photo credit should read ROBYN BECK/AFP via Getty Images)