The blast that ripped through a military convoy in the late morning also killed an Iraqi interpreter and wounded two other soldiers, the US military said on Monday.
The military deaths, the first in five days, brought to 202 the number of US soldiers killed by hostile fire since Washington declared major combat over in Iraq on 1 May.
Earlier, the US military admitted an Iraqi woman had been killed on Sunday as American occupation forces rounded up scores of people in a continuing crackdown in the Sunni heartlands of Iraq.
The woman was killed when US troops blew up the door of a house during a raid in the western town of Rawa near Iraq's border with Syria. The US military said the incident was under investigation.
The US Third Armoured Cavalry Regiment (3rd ACR) has been conducting Operations Rifles Fury in Rawa, a mission aimed "to kill or capture anti-coalition forces and destroy terrorist training camps", the US military said.
Overnight raids continued in the northern Sunni areas with US forces saying they had captured 40 "enemy personnel" in al-Anbar province.
Eight soldiers were wounded in the al-Anbar operation.
Another four soldiers were wounded, one of them seriously, when an explosive device detonated near the town of Habbaniya, a military statement said.
And in the northern city of Mosul one US soldier was wounded in small arms fire in a suspected resistance attack on Monday morning.
A raid on the town of Falluja resulted in the seizure of 25 people, including three on a wanted list.
Iraqi general held
Elsewhere, US occupation forces have arrested a former top officer in Saddam Hussein's security services suspected of directing anti-American attacks north of Baghdad, US officers said on Monday.
General Richard Myers says he
expects more resistance in Iraq
The man, a major-general in the former Iraqi intelligence department, was detained during overnight searches in Baquba, 65km north of Baghdad, they said.
Chairman of the US Joint Chiefs of Staff, General Richard Myers, said hundreds of Iraqis, including some resistance leaders, had been arrested following the capture of ousted leader Saddam Hussein.
Myers also said Saddam was not cooperating with US authorities who had been interrogating him since he was caught on 13 December near his hometown of Tikrit.
He told CNN television that some of the information had come from the briefcase seized when US forces found Saddam hiding in a hole under a farmhouse near his hometown of Tikrit.
Details of capture
More details have emerged about the circumstances of Saddam's arrest on 13 December.
A tribal chief in the northern Iraqi village of al-Dawr where
Saddam was captured claimed the ousted leader hid in the same farm where he had sought refuge as a young man in 1959 after a botched assassination attempt on then head of state Abd al-Karim Qasim.
Shaikh Hassib Shahib Ahmad, head of the al-Muwasat tribe, said the farm belonged to Qaiss Namach Jassam, the son of Jassam Namach who sheltered Saddam 44 years ago, before he fled Iraq after the failed murder attempt.
"Namach was offering the customary hospitality of the Arabs to a man who was wounded and in danger," he said.
Qaiss and his brothers were arrested after Saddam's capture by US troops, said the shaikh.