BAGHDAD, Iraq (CNN) -- Gunmen kidnapped 10 tribal sheiks in Baghdad as the men were heading home Sunday after meetings with Iraqi officials on the nation's contentious reconciliation process, an Interior Ministry official said.
Ermergency personnel respond Sunday after a suicide bomber attacked a commercial area in Kirkuk.
The sheiks -- seven Sunnis and three Shiites -- were riding in two vehicles through the capital's Shaab district, a stronghold of the Mehdi Army, the militia loyal to radical Shiite cleric Muqtada al-Sadr.
The sheiks were en route to Baquba, in Diyala province, when gunmen in several vehicles stopped their cars and kidnapped them, the official said.
The tribal leaders had just met with an official in Prime Minister Nuri al-Maliki's office in the Green Zone. Al-Maliki did not attend the meeting, a spokesman said.
It is not clear who staged Sunday's kidnappings, but it is not the first time insurgents have targeted reconciliation efforts, which are aimed at easing the sectarian tension and violence between Sunnis and Shiites.
Last month, a suicide bomber killed 24 people after attacking a Ramadan breaking-of-the-fast meeting in Diyala that brought together Sunni and Shiite military leaders.
Though the U.S. has called the Mehdi Army "the most dangerous accelerant" of Iraq's sectarian warfare, al-Sadr has called on his militia to observe a cease-fire with police and rival factions.
However, the U.S. military said Saturday it had captured a Mehdi "splinter group leader, who was not honoring Muqtada al-Sadr's pledge to cease attacks."
Car bombs in Kirkuk, Baghdad
Six civilians were killed and 25 others wounded when a car bomb exploded near a bus stop in Kirkuk, local police said.
The bomb detonated about 2:45 p.m. local time in al-Iskan, a commercial area of the northern Iraqi city.
The oil-rich city of Kirkuk is ethnically diverse, with large populations of Arabs, Kurds and Turkmen jockeying for power.
About 150 miles (240 kilometers) south, in the capital, a car bomb went off in Baghdad's predominantly Shiite Kadhimiya district, killing two civilians and wounding 10 others, an Interior Ministry official said.
U.S. to hand over Karbala
The U.S. military said it will hand over responsibility for security in Karbala province to the Iraqi army on Monday.
"After careful assessment by the multinational forces ground commander, the provincial governor and the Joint Committee to Transfer Security Responsibility, the Karbala Province was deemed ready to assume security responsibility in the region," the U.S. military statement said.
Karbala, a Shiite province south of Baghdad, will be the eighth of 18 Iraqi provinces to be handed over to the Iraqi government. The other provinces are Najaf, Muthanna, Dhi Qar, Maysan, Duhok, Erbil and Sulaymaniyah.
Karbala is considered to be more peaceful than other regions of the country despite that the handover was delayed by recent clashes between Shiite factions.
The U.S. military will remain in the province to support the Iraqi military when requested.
Ahmadinejad cries double standard
Iranian President Mahmoud Ahmadinejad accused the United States of applying a double standard because it is not acting against Kurdish rebels launching attacks against Turkey from northern Iraq.
Ahmadinejad's remarks came during a phone conversation with Turkish President Abdullah Gul on the same day that Turkey's prime minister said his country would not hesitate to send troops across the border. Watch why Turkey feels Iraq is doing too little to combat rebels »
The rebels, formally known as the Kurdistan Workers' Party, or PKK, are seeking to carve an independent state out of Iran, Iraq, Syria and Turkey.
The Turkish government -- which amid diplomatic pressure has refrained from launching a full-scale military operation -- wants Iraq to handle the rebels but says it can't wait indefinitely.
Turkish Prime Minister Recep Tayyip Erdogan warned Saturday that "whenever an operation is needed to be carried out, we will do that. We do not need to ask anything from anyone for that."
The United States, which believes an offensive will further destabilize the already volatile region, is working to prevent such an incursion.
U.S. Secretary of State Condoleezza Rice will be in Ankara on Thursday for bilateral meetings with Erdogan and Gul. Erdogan also is scheduled to meet President Bush at the White House on November 5. E-mail to a friend
CNN's Jomana Karadsheh contributed to this report.