United States officials implicated Zarqawi in over 700 killings in Iraq during the invasion, mostly from bombings. Since March 2004, that number rose into the thousands. According to the United States State Department, Zarqawi was responsible for the Canal Hotel bombing of the United Nations Headquarters in Iraq on August 19, 2003. This attack killed twenty-two people, including the United Nations secretary general's special Iraqi envoy Sergio Vieira de Mello. Zarqawi's biggest alleged atrocities in Iraq included the attacks on the Shia shrines in Karbala and Baghdad in March 2004, which killed over 180 people, and the car bomb attacks in Najaf and Karbala in December 2004, which claimed over 60 lives.