Iraqi authorities are assuming control of the mostly Shi'ite province of Karbala Monday.
U.S. forces in Iraq are planning to transfer security duties to Iraqi forces, making Karbala the eighth of Iraq's 18 provinces to be handed over to Iraqi control.
U.S. troops say they will step in if Iraq asks for help.
Karbala is home to the shrines of two revered Shi'ite saints, Imam Abbas and Imam Hussein. Rival Shi'ite militias have been struggling for power in the province.
In violence Sunday, Iraqi authorities say at least ten tribal leaders from Diyala province were kidnapped after meeting with a government official in Baghdad.
Police say the leaders, who are part of a group that opposes al-Qaida in Iraq, were ambushed while driving through the predominantly Shi'ite Shaab neighborhood.
Sources say militants shot one of the tribal leaders, but further details were not available.
Also Sunday, Iraqi authorities say at least 10 people were killed and more than 35 others were injured in separate bomb attacks.
Police say a car bomb killed two people and wounded at least 10 others near a market in northern Baghdad.
And authorities say a suicide bomber detonated explosives at a bus terminal in the northern Iraqi city of Kirkuk. Police say eight people were killed and at least 26 others were wounded in that attack.
Some information for this report was provided by AFP, AP and Reuters.