BAGHDAD, Iraq (CNN) -- A roadside bombing near Baghdad's volatile Sadr City neighborhood on Wednesday killed at least 11 civilians and wounded 20 others, an Interior Ministry official said.
A man rushes an injured child into the hospital in Baghdad on Wednesday after a roadside bomb explosion.
The incident occurred about 10:45 a.m. in Habibiya, at the southeast edge of Sadr City, a densely populated and predominantly Shiite neighborhood in Iraq's capital that's a stronghold of anti-American cleric Muqtada al-Sadr and his Mehdi Army militia.
In the northern Iraqi city of Mosul, a suicide car bomb at a checkpoint killed a policeman and wounded 28 other people, police said.
The bombing occurred around 3 p.m. in the southeastern part of the city, police said. The injured included street vendors and people in nearby houses, they said.
The U.S. military Wednesday reported the deaths of six U.S. soldiers in Baghdad -- two on Wednesday and four on Tuesday.
Two soldiers died in combat in eastern Baghdad on Wednesday, a military statement said.
On Tuesday, three U.S. soldiers were killed by a roadside bomb, also in eastern Baghdad, and one died in combat in western Baghdad, the military reported.
The number of U.S. military deaths in the Iraq war now stands at 3,750, including seven civilian employees of the Defense Department.
The bomb, known as an explosively-formed penetrator, detonated while the soldiers were on patrol during combat operations in the eastern section of the Iraqi capital.
The military has said for months that the high-tech, armor-piercing explosively-formed penetrators are supplied to insurgents in Iraq by Iranian operatives. Iran denies it.
U.S.-led coalition forces captured a "highly sought" individual with alleged ties to Iran early Wednesday during a raid south of Baghdad in the Shiite Muslim holy city of Karbala, a U.S. military statement said.
According to the military, the detainee was suspected of coordinating with high-level officers in Iran's Islamic Revolutionary Guard Corps-Quds Force, with the goal of taking Iraqis into Iran for terrorist training.
Although the coalition is still assessing the individual's connection with the Quds force, Multi-National Force-Iraq spokesman Lt. Col. Christopher Garver described the arrest as an "integral part of dismantling terror networks that seek to kill innocent Iraqis and security forces."
Coalition troops Wednesday killed a person described as "an al Qaeda in Iraq leader" and detained 18 "suspected terrorists" in a series of raids, the U.S. military.
"The al Qaeda in Iraq emir of the Arab Jabour area" south of Baghdad was killed, it said. The militant, who wasn't named by the military, "managed all terrorist attacks in the area south of Baghdad," the statement said.
The military said coalition troops were approaching a building when they came under small arms fire. They returned fire and killed one person, later determined to be "the terrorist emir." Eight other people were detained and weapons were found.
In northern Iraq, coalition troops detained 10 people during operations in the cities of Mosul and Baiji.
Also Wednesday, Iraq's first prime minister of the post-Saddam Hussein era said the current prime minister needs to step down from his post.
Ayad Allawi made the call for embattled Nuri al-Maliki to leave his job in an interview with CNN.
"If I were in his shoes, I would resign, I would not stay for a single second in office," said Allawi -- the first mainstream Iraqi politician to call for al-Maliki's resignation.
Allawi is making a major push to challenge al-Maliki's Shiite-dominated government and provide an alternative path for marginalized Sunnis, wavering Shiites and influential Kurds.
He has retained a U.S. public relations firm, Barbour Griffith and Rogers, which has ties to the Republican party to promote his agenda and challenge the ruling Shiite coalition.
Some American politicians, such as Sens. Carl Levin and Hillary Clinton, have also called on Parliament to select a new prime minister. Many U.S. politicians and officials have been upset with the lack of progress in political reconciliation, a major goal in restoring order in Iraq.
Allawi says al-Maliki, a secular Shiite, has ignored calls to rid the government of sectarian agendas and tolerance for Iranian influence.
Allawi also addressed other issues in the interview. He challenged an assertion in a recent report from the U.S. Government Accountability Office that Iraq is ensuring the rights of minority political parties -- one of the few benchmarks the government has met, according to the report.
"The Sunnis are being harassed and intimidated, and they've pulled out of the government. And the rest, the liberal forces like us, are being faced with pressure, extreme pressure. So this is really not a healthy democratic system we have," he said.
Allawi questioned President Bush's statement that recent military successes in turning Sunni tribes against al Qaeda in Iraq could lead to a decrease in U.S. troop levels.
"This is a phenomenon which will backfire at some stage," said Allawi, who warned that new Sunni militias could emerge from this effort unless the strategy is coordinated.
He said the Sunnis who are working with the U.S. must be legitimately integrated into the Iraqi military for the American effort to succeed. E-mail to a friend
CNN's Aneesh Raman and Raja Razek contributed to this report.