Kevin Lamarque / Reuters
Members of Congress and Capitol Hill staffers observe a moment of silence on the steps of the U.S. Capitol for Arizona Congresswoman Gabrielle Giffords in Washington, Jan. 10, 2011. A 22-year-old man has been charged with trying to assassinate Giffords in a shooting rampage that killed six people and wounded 14 in Tucson, Ariz. Giffords is fighting for her life in a Tucson hospital.
Chris Carlson / AP
Marcus Joiner, left to right, Jason Hoffman, Elijah Otero, and Allison Weiss reflect during a national moment of silence at the site of Saturday's shooting in Tucson.
Justin Lane / EPA
Traders observe a moment of silence on the floor of the New York Stock Exchange.
Matt Sullivan / Reuters
People attend a memorial service outside the Arizona State Capitol in Phoenix.
President Obama leads a moment of silence in memory of the victims of the mass shooting in Arizona.