Gunman shoots Rep. Gabrielle Giffords and kills six at Tucson constituent event

Jared Lee Loughner opened fire at Rep. Gabrielle Giffords' Congress on Your Corner event outside a Tucson grocery store, severely wounding Giffords and killing six people, including federal Judge John Roll. The mass shooting was one of the most notable attacks on a sitting member of Congress in modern U.S. history.