9/16: Washington Navy Yard employees ran for their lives as shooting began; Is Syria chemical weapons compromise feasible?
Hundreds of police, federal agents and first responders converged on the Washington Navy Yard just minutes after a gunman opened fire Monday morning. The shooting left at least 13 people dead; and, former U.N. arms inspector Richard Butler tells Scott Pelley it will be hard to be certain that Syrians have parted with all of their chemical weapons, but that if the Assad regime has "half a brain," it will cooperate.