In the Kirkuk incident, which happened late on Friday, two of the woman's relatives were wounded night when US soldiers opened fire on their car.
Police said the car failed to stop at a checkpoint in what is Iraq's northern oil capital, 250km north of Baghdad.
"An Iraqi woman was killed and two other women wounded by US shots at 10 minutes past midnight (2110 GMT) in the Askari district of Kirkuk," the city's police chief General Turhani Yusuf said.
"The car failed to stop at a checkpoint manned by the Americans. They opened fire, killing Shakra Ahmad Husain, 27, and wounding her sister and her mother."
Yusuf said the car's driver was unhurt.
It was not immediately possible to obtain comment from the US army in Kirkuk.
In a separate incident, four US military hardware contractors working for a US security firm were wounded on Saturday by a car bomb in northern Iraq, a military spokeswoman said.
Sergeant Cynthia Weasner, of the Tikrit-based 1st Infantry Division, said the four men, employed by Florida-based Cochise Security Inc, were wounded at about 7am (0400 GMT) near Baiji, 180km northwest of Baghdad.
US military contractors were hurt
in an ambush in Baiji on Saturday
Two of the security employees suffered minor wounds while the other two were taken to a mili-tary medical facility, the military said.
The attack came after US soldiers arrested five Iraqis, including two suspected weapons dealers, near Baiji on Friday during a raid to detain alleged car-bomb makers, according to a military statement.
Two vehicles suspected of being car bombs were discovered.
Cochise provides security personnel to assist in the disposal of Saddam Hussein-era munitions found in Iraq after the March 2003 invasion.
Three Cochise employees were killed by car bombs near Baiji in two separate attacks in April this year.
Military and security contractors assisting US-led forces in Iraq have been regular targets of anti-American forces.
Turkish truckers are regularly
targeted along Iraq's highways
In other incidents, several Turkish embassy guards were killed in an ambush as they travelled to Baghdad late on Friday night.
The Turkish foreign ministry did not specify how many guards died in the attack in Mosul but CNN Turk television put the number at four.
One of the guards and a driver survived the attack and returned to Turkey, while two other guards made it safely to the embassy in Baghdad.
"Our authorities are investigating the matter and trying to obtain more information from the Iraqi interim government and local officials," the statement added.