At least six civilians have been killed in a suicide attack south of Baghdad, Iraq's Interior Ministry said.
Spokesman Brigadier General Saad Maan said six suicide bombers tried to infiltrate the holy Shiite city of Karbala on Monday, but security forces managed to kill five of them.
Brig. Gen. Maan added that the sixth bomber broke into a house where he blew up himself, killing six people and injuring six others.
Hundreds of thousands of faithful Shiites have been walking to Karbala to commemorate the end on Sunday of the 40-day mourning period of the seventh century death of Imam Hussein, Prophet Muhammad's grandson. The city is some 55 miles (90km) south of the capital.
No group claimed responsibility, but suspicion fell on Sunni religious extremists who consider Shiites to be heretics.