BAGHDAD — Three U.S. soldiers were shot dead today in northern Iraq, and the decaying bodies of at least 23 Iraqis were discovered in a shallow grave and a sewer shaft at separate sites near the capital.

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-Qaida in Iraq.

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.

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 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-Qaida-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.