Crowds had gathered for a ceremonial ribbon-cutting
Dozens of children have been killed in a sequence of bomb blasts in Baghdad.
Officials said at least 34 children were among 41 or more people killed when bombs were detonated near a water treatment plant as US troops passed by.
At least 130 others were injured, many among crowds gathered for the opening ceremony at the plant who had gone up to collect sweets from the soldiers.
Two more blasts hit as people rushed to help those hurt by the first car bomb. Elsewhere, there was also bloodshed.
The casualties include:
- Two Iraqi policemen and a US soldier killed in the Abu Ghraib district of Baghdad by a car bomb that also left dozens injured
- A US soldier killed by a rocket fired at a US base near Baghdad
- A senior policeman shot dead in the northern city of Mosul
- Also in the north, the Kirkuk mayor's chief bodyguard shot dead
- Four people killed in a car bombing in Talafar that also injured about 16 others
- At least four children among six or seven people killed in Falluja after US forces allegedly fired on their car
- At least three civilians killed in a US air strike on Falluja overnight.
Reports from Baghdad said hospitals struggled to cope with the mass influx of casualties from the apparently co-ordinated bombings in the poor south-west al-Ummal district.
Many victims were caught trying to help those hit in the first blast
Many of the injured - who included 10 US soldiers - suffered shrapnel wounds in the blasts which began at about 1300 (0900 GMT), correspondents said.
Pools of blood formed on the hospital floors, while at the scene of the blasts, people picked through blood-stained wreckage to recover body parts, news agencies said.
Children who survived the attack described how they had been rushing towards the US convoy to collect sweets from the troops.
"The Americans called us, they told us come here, come here, asking us if we wanted sweets," 12-year-old Abdel Rahman Dawoud told the Associated Press news agency from his hospital bed where he lay naked, with shrapnel embedded all over his body.
"We went beside them, then a car exploded."
Officials say the first blast was soon followed by another car bomb and then the explosion of a device on the road. It remains unclear whether the convoy or the crowds were the prime target.
"This attack was carried out by evil people who do not want the Iraqis to celebrate and don't want [construction] projects in Iraq," National Guard Lieutenant Ahmad Saad told the Associated Press news agency at the scene.
The BBC's Caroline Hawley in Baghdad says the sequence of explosions was a highly co-ordinated attack to prevent the reconstruction of Iraq, as well as spreading fear.
Violence continued in the restive city of Falluja, where doctors said a woman and a child were among at least three people killed when US forces launched air strikes on a house.
The military said it targeted supporters of the Islamic militant, Abu Musab al-Zarqawi, who is blamed for a string of kidnappings and suicide bombings.
Falluja has come under repeated US attack
"Several intelligence sources reported that Zarqawi terrorists were using the safe house at the time of the strike to plan attacks against Iraqi citizens and multinational forces."
It said "significant secondary explosions during the impact" suggested arms had been stored in the house.
Iraq's interim Deputy Prime Minister Barham Saleh said the government was determined to retake rebel cities like Falluja within weeks and to hold elections as planned early next year.
"We aim to regain control of these areas before the month of November," he told reporters, expanding on earlier remarks by interim Prime Minister Iyad Allawi that "decisive action" was being planned for Falluja. "The government is determined to go ahead with elections... the elections will be held as scheduled," Mr Saleh insisted.