The U.S. military says four American soldiers were wounded and an interpreter was killed when gunmen attacked a police station in northern Iraq.
A second Iraqi interpreter was wounded.
Iraqi security sources say two people dressed in Iraqi police uniforms opened fire Tuesday in the city of Mosul in Nineveh province and then fled the scene.
Authorities have not said who was responsible for the attack. Mosul is considered the last major stronghold for Sunni extremists.
On Monday, the U.S. military said that three American soldiers and an interpreter were killed during combat operations in Iraq's Diyala province north of Baghdad.
Meanwhile, Iraqi authorities have arrested a group of Shi'ite former security officers accused in the killing of Sunni Arabs, including a vice president's sister.
Eleven former Interior Ministry employees are accused of carrying out attacks during the height of sectarian violence in Iraq.
The sister of Vice President Tariq al-Hashemi, Maysoon al-Hashemi, was shot and killed in Baghdad in April, 2006. Shi'ite militants have long been accused of infiltrating the Interior Ministry, using the cover of their positions to carry out crimes against Sunnis.
Sectarian violence has eased considerably in the past year, though occasionally flares up. Among the most recent victims were Shi'ite pilgrims who came under attack while marking a religious holiday earlier this month.
Some information for this report was provided by AP and Reuters.