Attacks in Iraq have killed at least 34 people and injured more than 100.
Officials said that a double explosion struck near a bus station in Babil province on Thursday, killing 15 people including a provincial councillor.
The first bomb, in a car, was said to have exploded at about 2pm (11:00GMT) in Hilla, the provincial capital about 95km south of the capital Baghdad.
Another blast came about 15 minutes later when police arrived.
The authorities said that the attacks targeted Shia worshippers who gathered near the bus station to mark Ashoura, a commemoration of the death of Prophet Muhammad's grandson, Hussein bin Ali.
In the northeastern Shia area of Sadr City in Baghdad, a bomb planted near a commemoration ceremony killed five people and wounded 25 others. Another bomb killed three people in the same neighbourhood.
Ahmed Rushdi, a journalist in Baghdad, told Al Jazeera: "The blasts happened nearly at the same time.
"They were not by the hand of al-Qaeda - they were not suicide bombers, but mostly car bombs and booby trapped cars."
Also on Thursday, a bomb blast killed one person and injured four others in the Shia sacred city of Karbala, about 100km south of Baghdad, police said.
In Mosul, 450km to the north of Baghdad, a Christian man was shot dead as he was parking his van in front of his house, police source said.
On Wednesday, six people were killed and another 43 people were injured in Baghdad in three explosions targeting Shias.
Thousands of Shias are expected to converge on the central city of Karbala for the December 27 Ashoura holiday to mourn the Prophet Muhammad's grandson, Imam Hussein, killed by armies of the Ummayad Caliph, Yazid bin Abi Sufian in 680 AD.
More than 25,000 security personnel have been assigned to protect pilgrims during the celebrations.