It was the fourth attack in 24 hours on Americans in Iraq, and the third with deadly results either for Americans or Iraqis.
The Pentagon has been playing down the attacks, saying they don't indicate widespread resentment on the part of the Iraqi people. Now, reports CBS News Correspondent Elizabeth Palmer, Iraq's first-ever public opinion poll seems to back that up.
Sixty-five percent of Iraqis polled in Baghdad claimed they want the U.S. military to stay until Iraq is stable and secure; only 17 percent want American soldiers out now.
But some U.S. lawmakers are increasingly uneasy about the daily killings of soldiers, the stretching thin of troop forces, excessive demands on reservists and the costs of the war.
The ambulance hit in the latest attack was transporting a wounded U.S. soldier to a medical facility when it was hit on a highway in southwest Baghdad.
The wounded soldier who was being transported was not the one killed, said Capt. John Morgan, a U.S. military spokesman in Baghdad. The casualties were members of an Army medical brigade and their identities were not being released pending notification of relatives.
The wounded were taken to an Army support hospital in southwest Baghdad. It was not immediately clear if the ambulance was traveling as part of a convoy or if fire was returned.
In other recent developments:
About a dozen U.S. servicemen have been killed by hostile fire in Iraq since President Bush declared major combat over on May 1. American military commanders in Iraq say attacks on their forces happen daily, though one commander on Tuesday dismissed the fighting as "militarily insignificant."
Deputy Defense Secretary Paul Wolfowitz and Marine Corps. Gen. Peter Pace, vice chairman of the Joint Chiefs of Staff, told a Congressional committee they believed the burden on U.S. forces would ease as more coalition forces enter Iraq. Pace said two additional divisions should be added in August or September to the 12,000 non-U.S. forces now in Iraq.