BAGHDAD, Iraq (AP) – Two bombings 20 minutes apart killed at least 11 Iraqis on Thursday, 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.

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.