The Americans were killed when gunmen opened fire on them in the northern Iraqi village of Hawija, according to a brief military statement.
The area, once a hub for Sunni militants and disaffected allies of Saddam Hussein, is thought to have been pacified in recent months. Last year it hosted one of the largest sign-on ceremonies for tribal sheiks partnering with U.S. forces to fight al Qaeda in Iraq.
The latest U.S. deaths brought to at least 4,090 the number of U.S. military personnel who have died in the Iraq war since it began in March 2003, according to an Associated Press count.
South of Baghdad, Iraqi villagers and soldiers unearthed at least 13 bodies from a shallow, dusty grave in farmland on the outskirts of Latifiyah, a mostly Sunni town that also has some Shiite residents. The bodies were first discovered Tuesday, but digging continued a day later.
Associated Press Television News footage showed Iraqi troops and civilians clawing through dusty soil with shovels. At least three severely decomposed bodies could be seen in side-by-side graves. One had a turban or bandage tied crudely around his head.
The U.S. military could not confirm the discovery, but said its soldiers, acting on a tip from a local citizen, found at least 10 decomposed bodies Tuesday in a separate location, in the sewer shaft of a building in east Baghdad.
Those victims appeared to have died more than two years ago, said Lt. Col. Steve Stover, with the Army's 4th Infantry Division. Iraqi police have taken over the investigation, he said.
Latifiyah, which lies about 20 miles south of Baghdad, was taken over by al Qaeda-linked militants a few years ago, and became a hotbed of Sunni militant activity before U.S. and Iraqi forces regained control late last year, said Iraqi Maj. Faisal Ali Hussein, who supervised that digging Tuesday.
Only now are villagers - feeling safer without the militants there - beginning to point out possible sites of mass graves in the area, he said.
Most of the bodies were too decomposed to identify and they were reburied next to where they were discovered, said another Iraqi army officer at the scene, who refused to give his name because of safety concerns.
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