BAGHDAD -- Iraq's Interior Ministry says a suicide attack south of Baghdad has killed at least six civilians.

Ministry spokesman Brigadier General Saad Maan says six suicide bombers tried to infiltrate the holy Shiite city of Karbala on Monday, but security forces managed to kill five of them.

Maan added that the sixth bomber broke into a house where he blew himself up, killing six and wounding six.

Hundreds of thousands of faithful Shiites have been walking to Karbala to commemorate the end of the 40-day mourning period of the seventh century death of Imam Hussein, Prophet Muhammad's grandson on Sunday. The city is located is some 90 kilometers (55 miles) south of Baghdad.

No group claimed responsibility, but suspicion fell on Sunni religious extremists who consider Shiites as heretics. (AP)