The responsibility of the attack was claimed by Islamic State. It claimed that as many as 200 people had been killed and wounded in the blast, in a statement delivered by its news agency. The Sunni extremists of IS consider Shia to be apostates worthy of punishment by death for their veneration of the Prophet’s family and other beliefs and practices. The pilgrims were en route back to Iran from the Iraqi Shi’ite holy city of Karbala, where they had commemorated Arbaeen. The road stop was full of people. Iranians were among the victims of the blast. Officials said IS militants attempted to infiltrate Karbala last week when five of the six bombers were shot dead.