The U.S. State Department confirmed that at least 80 people, mostly Iranian Shi'ite pilgrims were killed and 50 injured on Thursday when a truck bomb exploded at a gas station in Iraq. The ISIS claimed responsibility for the attack in a statement posted online.
"The flames of battles in Mosul will reach them in Baghdad, Karbala and Najaf," the ISIS statement reads, according to CNN.
The parked truck exploded near several buses carrying Shi'ite pilgrims, who were in Iraq to commemorate Imam Hussein's death.
Hussein was the grandson of the Prophet Mohammed and was killed during a battle near Karbala for control of the Muslim nation.
Hussein's 7th-century death led to a split between Sunni and Shi'ite Muslims that still divides the sects today.
Despite ongoing dangers, Shi'ite pilgrims still make the journey to Karbala.