Blast Kills 27 in Iraqi Shi'ite City of Karbala

Iraqi police say at least 27 Shi'ite pilgrims have been killed and 56 wounded in a bombing on the outskirts of the holy city of Karbala, south of Baghdad.

There are reports of both a car bomb and mortar attacks.

The bombing is one of several that struck this week as hundreds of thousands of Shi'ite pilgrims flocked to the city on the most important day of a Shi'ite pilgrimage, Arbain.  It marks the end of 40 days of mourning for the death of Imam Hussein, a revered 7th-century Shi'ite cleric.  

Wednesday, a motorcycle bomb exploded as pilgrims made their way to Karbala, and two separate roadside bombs targeted Shi'ite pilgrims in Baghdad.  These attacks killed at least 24 people and wounded many others.

And on Monday a female suicide bomber blew herself up among a crowd of Shi'ite pilgrims in Baghdad, killing at least 41 people and wounding more than 100 others.

Sunni insurgents in Iraq have routinely attacked Shi'ite pilgrims in recent years in a campaign to ignite a sectarian conflict.