Security concerns are running high as reports claim that a three-year old was killed and seven pilgrims injured, following an ISIS mortar attack near Karbala city on Friday.
This year, a record number of pilgrims - 17.5 million - from Iraq and Iran are heading to Karbala for the religious ceremony, despite a threat by ISIS to bomb the site.
While the local security forces along with the Iraqi militia are working on the security around Karbala, reports claim that the ISIS militants have been able to sneak into the province.
Initial reports claimed that in three mortars fired by the Islamic State near Karbala, a three-year-old was killed, while seven were injured.
Despite the looming threat, millions of faithful, including some Sunnis, Yazidis and even Christians have been arriving at the holy city, where Imam Hussein was killed in a battle and beheaded in 680 AD.
Imam Hussein is one of the most revered figures for Shiites, who are the largest community in Iraq and has an overwhelming majority in the neighbouring Iran. Saturday will mark the end of a 40-day period of mourning to mark the anniversary of Imam Hussein's death.
However, Sunni militant groups such as al-Qaeda and Islamic State consider Shiites to be heretics and often target the pilgrims.
This year's pilgrimage has taken on a major geo-political dimension as it is the first time that a major Shia-led event is being held, after ISIS took over large territories in Iraq and Syria.