BAGHDAD, Iraq — A body clothed in an American military uniform was found yesterday morning floating down the Euphrates River 12 miles south of the site where three soldiers were previously abducted.

Iraqi police said the body was probably that of one of the three missing soldiers, but Major General William Caldwell said the corpse had not been identified. The soldiers were ambushed and abducted in a May 12 attack that left four American soldiers and an Iraqi translator dead.

An Iraqi police officer who responded to the scene said onlookers reported two additional corpses in the river clothed in American military uniforms. But the witnesses reported that the bodies became submerged, and an American search team has not yet uncovered them.

The features of the recovered body were difficult to discern because the man appeared to have been dead for days and about half a dozen gunshots wounds covered his face, skull, and neck, the officer said. The arms and chest appeared to have suffered blows from a pipe. One of the only distinguishing characteristics that Iraqi police were able to make out was a tattoo on the left hand, he said.

The body was discovered about 11 a.m. local time by shoppers near a marketplace in Musayyib, a small collection of slums 40 miles south of Baghdad.

Two police officers and a civilian swam into the river to recover the corpse. When they returned to shore, they realized it was clothed in the uniform of an American soldier, and American forces were quickly summoned.

The missing soldiers are Private First Class Joseph Anzack Jr., 20, of Torrance, Calif.; Specialist Alex Jimenez, 25, of Lawrence, Mass.; and Private Byron Fouty, 19, of Waterford, Mich.

They have been the subject of a huge dragnet. Yousifiya, a market town of about 5,000 people 10 miles south of Baghdad, has served as the staging point for the search and has received hundreds of extra troops.

More than 900 local residents have been detained, and an American soldier was killed when an improvised bomb hit his unit as they searched by foot.

“We continue to remain prayerful and hopeful that we will find safely all three of our American missing soldiers,” General Caldwell said in a news conference yesterday afternoon.

The American military in Baghdad said nine soldiers and Marines were killed in five roadside bomb and shooting attacks across Iraq on Monday and Tuesday.

A suicide bomber killed 20 civilians and injured 30 in Mandili, a town of Shiite Kurds in northeastern Iraq. Just south of Baghdad’s Green Zone, gunmen stormed a marketplace, shooting customers. Four civilians were killed and 11 were injured, authorities said.