Karbala: A deadly mortar attack on Friday near the Iraqi city of Karbala stoked security concerns as millions of Shi'ite pilgrims gathered for one of the largest religious gatherings in the world.
"There were one person killed and four wounded when mortar rounds hit an area on the western side of the city" shortly after midnight, a police colonel said.
"They crashed into an area called Souk al-Basra, around seven kilometres (four miles) from the city centre," he said, adding the victims were residents and not pilgrims.
A medical source in the holy city of Karbala confirmed the toll.
Record numbers of Shi'ite faithful have been converging on Karbala from across Iraq and other countries for Arbaeen, which on Saturday will mark the end of a 40-day period of mourning following the anniversary of Imam Hussein`s death.
Hussein is one of the most revered figures for Shi'ites, who are the largest community in Iraq and the overwhelming majority in neighbouring Iran.
Defence Minister Khaled al-Obeidi said on Thursday that more than 17 million pilgrims had come to Karbala for Arbaeen, which in a normal year is already considered one of the largest religious gatherings in the world.
The Karbala governor has said this year`s was the biggest on record.
This year`s pilgrimage has taken on a political dimension as it is the first since the devastating offensive the Islamic State group launched in Iraq in June.
The jihadist organisation -- led by Sunni extremists -- considers Shi'ites to be heretics and has made targeting the community one of its main objectives.Millions of faithful have for days been converging on the holy city where Hussein was killed in battle and beheaded in 680 AD, entire families trekking for days on the roads and sleeping in the open.
Central Baghdad has been in lockdown mode much of the week as authorities restricted access and movement in order to avoid a complete logjam and minimise the risks of major bomb attacks.
Three people were killed and four wounded earlier this week, according to security and medical sources, when a bomb went off in northeastern Baghdad near one of the thousands of tents set up to serve food and beverages to marching pilgrims.
However, given how exposed the pilgrims are and what a prime target they are for IS fighters, very few incidents have been reported so far.
Iraqi officials have stressed how crucial a recent military victory against the jihadists in the Jurf al-Sakhr area has been in making the pilgrimage possible.
The continued presence there of IS fighters would have exposed the millions of southbound pilgrims walking through an area which has seen some of the worst sectarian violence of the past decade and been dubbed the "triangle of death".
Shi'ite militias have played a leading role in the battle for Jurf al-Sakhr, an area between Baghdad and Karbala where jihadists were supplied from their strongholds in the western Anbar province and which has seen some of the fiercest fighting since June.
Communications Minister Hassan al-Rashed told a news agency earlier this week that fighters who took over former IS positions in Jurf al-Sakhr found evidence that the jihadists had been planning to target Karbala.
Rashed is also a commander in the Iran-backed Badr organisation, which also holds the interior ministry in Iraq`s new government and whose military wing is one of the largest militias in the country.
The bombing of a revered Shi'ite shrine in the city of Samarra in February 2006 was the main trigger for a bloody sectarian war between Iraq`s Sunnis and Shi'ites.