Lieutenant Colonel James Hutton said that three soldiers were killed and another wounded in the explosion of a makeshift bomb in a western district of Baghdad.
Another two soldiers were killed and three wounded on Friday in two separate incidents in the capital, bringing to 1,412 the total number of US servicemen who died in Iraqi since the invasion almost two years ago.
An OH-58 Kiowa Warrior, a reconnaissance chopper from the same Baghdad-based division, crashed in a south-western district of the capital, but there was no word on the fate of the two-man crew.
"At this time, we have no evidence of hostile fire playing a role in the helicopter going down," Colonel Keith Walker said in a statement.
Earlier on Friday, four people were killed in a suicide car bomb attack at a power station in the southern Baghdad neighbourhood of Dura, police and medical sources said.
"At around 9:00 am (0600 GMT), a black GMC approached the checkpoint at the entrance of the power plant. There was only a driver inside the car, his face was masked," a policeman who witnessed the attack told AFP.
"He was stopped at the checkpoint and a few seconds later, the explosion went off. We lost three comrades and one civilian was also killed in the blast," said the policeman.
He was speaking from Baghdad's Yarmuk hospital, where medical sources at the emergency department confirmed the death toll and added that three other policemen and a civilian were also wounded in the attack.
The bullet-riddled bodies of six Iraqi soldiers were found on Friday in the western city of Ramadi, where two more people were killed and eight wounded in fighting between Iraqi forces and insurgents.
"The bodies of six soldiers, with their dog-tags, were found in central Ramadi," a police officer told AFP on condition of anonymity.
It was the latest in a series of finds of bodies of apparently executed security personnel in the city. Iraqi troops traded fire with the Sunni Muslim insurgents Friday, in a gunfight in which a soldier and a civilian were killed, Lieutenant Colonel Mahmud Mohammed said.
Four women and four children were also wounded by mortar fire on Thursday night, said Doctor Alaa al-Rawi of the city's hospital.
An Iraqi policeman was killed and two civilians wounded in a host of attacks on buildings to be used as voting stations around Kirkuk, 250 kilometers north of the capital.
The policeman was shot dead by attackers as he stood guard at a voting station in the east of Kirkuk, which has a divided population of Kurds, Arabs and Turkmen, police told AFP.
A car bomb attack went off near a school to be used as a polling station in the same Baghad neighbourhood where the power station was targeted. A police officer said the blast caused material damage but no casualties.
But an Iraqi soldier was killed and another wounded when their patrol vehicle ran over a mine near Samarra, in the "Sunni Triangle" north of Baghdad, police said.
Other attacks were reported in the triangle. One man was wounded in an attack on another polling station at Al-Dur and another civilian was injured in a mortar attack on a voting centre in Tikrit, Saddam Hussein's hometown.
Dozens of voting stations have been attacked by insurgents who have put up posters and handed out leaflets warning Iraqis not to vote.