At least three incidents are currently known to be under investigation:
U.S. commanders have ordered new ethics training for all troops in Iraq. But the flow of revelations and investigations threatens to undermine Iraq's new government and public support in America for President Bush's management of the war.
With media attention increasing and Iraqi officials launching investigations into suspect killings, American military leaders are scrambling to curb the damage and to head off any more trouble.
Defense Secretary Donald Rumsfeld said Friday U.S. troops are "trained not to" massacre civilians.
Rumsfeld refused to comment directly on the ongoing investigations of U.S. forces, but he said "things that shouldn't happen, do happen" in combat. He said "99.9 percent of our forces conduct themselves in an exemplary manner."
Brigadier Gen. Donald Campbell, the chief of staff for the Multinational Force in Iraq, said the military will not accept behavior that is "morally, legally or ethically questionable." Campbell said "every incident or allegation" strikes a blow against American credibility — a commodity he said is too valuable to squander.
"It looks like the killing of Iraqi civilians is becoming a daily phenomenon," the chairman of the Iraqi Human Rights Association, Muayed al-Anbaki, said Friday after video ran on television of children and adults slain in a raid in Ishaqi in March.
Al-Anbaki's comments came a day after Prime Minister Nouri al-Maliki upbraided the U.S. military over allegations that Marines killed two dozen unarmed civilians in Haditha, calling it "a horrible crime." They were his strongest public comments on the subject since his government was sworn in last month.
Maj. Gen. William Caldwell, spokesman for U.S.-led forces in Iraq, said at a news conference Thursday that "about three or four" inquiries were being carried out around the country, but he would not provide any details.
CBS News correspondent Elizabeth Palmer reports that, while these stories are getting a lot of attention in the United States, they aren't having the same effect inside Iraq. The sad truth is that many Iraqis already assume that U.S. troops kill civilians indiscriminately, Palmer reports, and Iraqis are numbed by the daily violence.
The latest controversy relates to a March raid on the village of Ishaqi, in a Sunni-dominated area some 50 miles north of Baghdad.
Pentagon officials told CBS News National Security correspondent David Martin that 11 civilians were killed in a March 15 raid by American special forces.
The investigation found that the civilians were not killed deliberately reports Martin, but they were killed accidentally during a shoot out with insurgents holed up in a house.
An initial military report from the incident says that the soldiers received a tip that an al Qaeda supporter was visiting a house. The earlier report says that after a firefight, the civilians, including women and children, were killed when the house collapsed, Palmer reports.
Video shot by an AP Television News cameraman shortly after the raid – which shows at least five children dead – sparked interest in the Ishaqi raid when it was broadcast for the first time on Friday. The video shows at least one adult male and four young children with obvious entry wounds to the head. One child has an obvious entry wound to the side caused by a bullet.
The video includes an unidentified man saying "children were stuck in the room, alone and surrounded."
"After they handcuffed them, they shot them dead. Later, they struck the house with their planes. They wanted to hide the evidence. Even a 6-month-old infant was killed. Even the cows were killed too," he said.
The video shows the bodies of five children and two men wrapped in blankets.
Other video showed the bodies of three children in the back of a pickup truck that took them to the hospital in Tikrit, Saddam Hussein's former hometown.
Police Capt. Laith Mohammed said the March 15 attack that hit Ishaqi involved U.S. warplanes and armor.
Riyadh Majid, who identified himself as the nephew of Faez Khalaf, the head of the household who was killed, told AP at the time that U.S. forces landed in helicopters and raided the home.
Khalaf's brother, Ahmed, said nine of the victims were family members who lived at the house and two were visitors.