A bomb went off near a U.S. convoy in Iraq today that contained nerve gas.

A roadside bomb containing deadly sarin nerve agent exploded near a U.S. military convoy, the U.S. military said Monday. It was believed to be the first confirmed finding of any of the banned weapons upon which the United States based its case for the Iraq war. Two people were treated for ''minor exposure,'' but no serious injuries were reported.

The deadly chemical was inside an artillery shell dating to the Saddam Hussein era that had been rigged as a bomb in Baghdad, said Brig. Gen. Mark Kimmitt, the chief military spokesman in Iraq....[A spokesman for the Iraq Survey Group] believed that insurgents who rigged the artillery shell as a bomb didn't know it contained the nerve agent, and that the dispersal of the nerve agent from such a rigged device was very limited....It was unclear if the sarin shell was from chemical rounds that the United Nations had tagged and marked for destruction before the U.S. invasion.

Update: Weapons inspectors say it's not a sign that Iraq had stockpiled WMD.