BAGHDAD, Iraq (CNN) -- Four Americans -- two soldiers and two civilians from the Defense and State departments -- were killed Tuesday in a blast that rocked a municipal building in Baghdad's Sadr City, the U.S. Embassy said.
The attack also killed six Iraqis and wounded 10 others, an Iraqi Interior Ministry official said.
A second employee from the U.S. Defense Department also died, but that person wasn't an American. The employee was a dual Italian-Iraqi national, the Italian Foreign Ministry said.
The U.S. military said the blast struck a meeting of a district advisory council, a neighborhood group that looks at local needs and passes on its assessments to the provincial government.
The deputy head of the council was seriously injured, the Interior Ministry official said.
The U.S. military blamed Iranian-backed militants it calls Special Groups for the blast and detained three people in connection with the attack, including a suspect "fleeing the scene [who] tested positive for explosive residue."
"We believe the target of the attack was a high-ranking [district advisory council] member as well as the U.S. soldiers," said Lt. Col. Steve Stover, a U.S. military spokesman.
"We believe the Special Groups criminals were upset that the DAC member was working with coalition forces to improve the quality of life for the southern Sadr City residents."
A statement from Ryan Crocker, U.S. ambassador to Iraq, identified the slain State Department employee as Steve Farley.
"Mr. Farley was a member of our embedded Provincial Reconstruction Team for the Sadr City and Adhamiya districts of Baghdad City," the statement said.
"We extend our deepest condolences to their families and friends, and our profound appreciation for the ultimate sacrifice that they made in service to their country and for the people of Iraq. This is a tragic loss and one we all mourn."
The U.S. Embassy statement didn't identify the other victims.
The blast dramatizes the perils the war still poses for Americans despite a Pentagon report Monday that touted a sharp decrease in violence in Iraq in recent months.
The explosion also marked the third strike in two days involving local politicians and political institutions in Baghdad.
A city councilman on Monday fired on U.S. forces at a municipal building southeast of the capital in the Salman Pak area and killed two soldiers.
Separately, the head of Abu Dsheer City Council in Baghdad's southern Dora area was gunned down at his home later Monday.
Last week, a bomb ripped through Baghdad's Hurriya district near a neighborhood advisory council meeting where U.S. troops were stationed, killing 63 people and wounding 71 others.
The U.S. military also blamed that attack on a Special Groups cell, but Stover couldn't say whether it was connected to Tuesday's blast.
"Last week's event was an attempt to incite sectarian violence and hatred against the Iraqi Sunni population in an effort to keep them from returning to Hurriya," Stover said.
Sadr City, the scene of Tuesday's deadly blast, is a stronghold of Shiite cleric Muqtada al-Sadr and where some of the capital's most intense fighting in recent months has occurred between Shiite militia members and Iraqi security forces.
A truce deal was reached last month between the Iraqi government and al-Sadr's followers, ending weeks of fighting and allowing the Iraqi army to enter Sadr City, but violence persists.
Al-Sadr recently announced his intention to develop a new fighting force that would battle U.S.-led forces in Iraq.
Many followers in al-Sadr's Mehdi Army militia have heeded a long-standing cease-fire, but some rogue forces are thought to be involved in violence.
"This was the fourth meeting of this district council, led by hard-working Iraqis determined to make a difference and set Sadr City off on the right path. Special Groups are afraid of progress and afraid of empowering the people," Lt. Col. John Digiambatista of the 4th Infantry Division said in a news release, referring to Tuesday's attack.
Twenty-five U.S. troops have died in Iraq to date this month. There have been 4,109 deaths of U.S. service members since the war began.
• Three U.S. soldiers and their Iraqi interpreter were killed Tuesday evening by a roadside bomb in northern Iraq's Nineveh Province, the U.S. military said. No other details were immediately released.
• A suicide car bomb went off near a police station in central Mosul Tuesday evening, killing a child, a police officer and wounding dozens more. Police and civilians, including women and children, were among the wounded, though injury reports varied from 90 to 70 to 57, according to the U.S. Military, Mosul police and the Iraq Interior Ministry, respectively. All three sources agreed on the death toll, however. Several houses were affected by the blast, which destroyed a coffee shop in a residential area.
• Earlier Tuesday, coalition troops in Mosul killed a senior-level al Qaeda in Iraq leader, the U.S. military said. The operation led to the killing of the group's "emir" of Mosul, the military said. A dozen people were detained in raids targeting the group in northern Iraq and Baghdad, the military said.
• U.S. troops raided a Shiite militant hideout Tuesday in southeastern Baghdad's Karrada district, capturing four suspects the military said were connected to recent attacks on coalition bases. A vehicle bomb being built in the hideout was destroyed, according to a coalition statement.
• Anbar province will soon be run by the Iraqi military. The U.S. military said it is transferring security responsibility this week to the Iraqis. Anbar is the 10th of the 18 provinces where Iraqi forces have taken charge of security control since 2003 and the first largely Sunni Arab province to do so.
CNN's Yousif Bassil and Jomana Karadsheh contributed to this report.