Gunmen attacked the house of the head of Iraq's leading Sunni Muslim religious organization on Saturday, a spokesman for the Muslim Clerics Association said. He said gunmen showed up in cars and opened fire at the Baghdad house of Harith al-Dari in the morning and security guards returned fire. The apparent attack, which could not be immediately confirmed by police, came after the worst escalation in sectarian violence since the U.S. invasion of 2003. More than 200 Iraqis were killed in the 48 hours following the bombing of a Shi'ite shrine in the northern Iraqi city of Samarra on Wednesday, which prompted reprisal attacks on Sunni mosques, according to a report of Reuters. The violence had begun to ebb on Friday after the government imposed a day-time curfew.