A car bomb explosion tore through a crowd of Shiite pilgrims returning home from a religious commemoration, in Iraq killing at least 20, officials say.
The blast erupted in the town of Musayyib, about 60 kilometres (40 miles) south of the Iraqi capital Baghdad.
It targeted worshippers returning from the Shiite holy city of Karbala following the climax of the religious commemoration known as Arbaeen.
Children were among the 20 people confirmed killed, according to police. At least 50 people were wounded.
The explosion went off in the middle of a gathering of pilgrims changing buses coming from Karbala on their way to other destinations in the country.
Today marked the height of Arbaeen, when hundreds of thousands of Shiite pilgrims converged on Karbala to mark the passing of 40 days after the anniversary of the seventh century martyrdom of the revered Shiite saint Imam Hussein, the grandson of the Prophet Mohammed.
Shiite pilgrims are one of the favourite targets for Sunni insurgents during Shiite religious events.
Iraqi authorities typically tighten security in Karbala and along routes used by pilgrims, but security forces acknowledge they are unable to prevent all attacks.
As in previous years, the pilgrims practised the ritual of self-flagellation on the streets, hoisted Shiite religious flags on trees and lamp posts and served food from tents pitched on street corners.
State television earlier aired video of Prime Minister Nouri al-Maliki walking among the pilgrims.
The attack came after Iraqi authorities ordered the release of 11 women facing criminal charges and pledged to transfer other women prisoners to jails in their home provinces
The move appeared aimed at addressing a main demand during a wave of protests by the country's Sunni minority against the Baghdad government.
The demonstrations erupted following the arrest of bodyguards assigned to Finance Minister Rafia al-Issawi, one of the central government's most senior Sunni officials.
The protests tap into deeper Sunni feelings of perceived discrimination and unfair application of laws against their sect by Shiite Prime Minister Nouri al-Maliki's government.