Baghdad, Iraq ? Two bombings 20 minutes apart Thursday killed at least 11 Iraqis, and the U.S. military announced five more American battle deaths. A U.S. rocket attack on the Shiite stronghold of Sadr City killed a woman and enraged Shiites across Iraq.

Near Sadr City, a shepherd made a grisly discovery: 16 blindfolded and bound men who had been shot repeatedly and buried in an open area. The men, all wearing civilian clothes but with no identity documents, were the latest victims in a string of presumed sectarian attacks.

The bloodshed, coupled with attacks on an oil processing plant in the northern city of Kirkuk, underscored the difficulties faced by the U.S.-led coalition and Iraqi authorities in curbing Iraq’s raging violence.

A car bomb exploded about 5 p.m. outside a gasoline station in the eastern New Baghdad neighborhood, killing two people and wounding 13, police said. U.S. troops cordoned off the scene as firefighters battled giant plumes of bright orange flames.

About 20 minutes later, a suicide attacker apparently trying to target a Shiite mosque exploded his bomb-packed car in a nearby open-air market in New Baghdad, killing at least nine people and wounding 57, police said.

The bombings followed a morning barrage of rockets fired by a U.S. helicopter into the nearby eastern Baghdad area of Sadr City, power-base of radical anti-American Shiite cleric Muqtada al-Sadr.

The five American troops died Wednesday in three attacks, the U.S. command said.

A roadside bomb blast killed three U.S. soldiers south of Baghdad, while a fourth soldier died from wounds suffered in a small-arms fire attack in Baghdad, the military said. A U.S. Marine was killed during combat near the western city of Fallujah.