Group claims responsibility for deadly Iraq attacks February 24, 2012 -- Updated 1731 GMT (0131 HKT) The Islamic State of Iraq claims responsibility for Thursday's attacks The group includes al Qaeda in Iraq The group threatens to track down and target Shiite officials Baghdad (CNN) -- The Islamic State of Iraq has claimed responsibility for Thursday's attacks in that country that killed dozens of people and wounded hundreds more. The umbrella group, which includes al Qaeda in Iraq, issued an audio message that was posted on an al Qaeda-linked website. "Shiite forces have been conducting campaigns, targeting Sunni people inside their homes day and night," the group's spokesman, Abu Mohammed al-Adnani, said in the message. "I am calling on Sunni people in Iraq to wake up before it's too late and put their hands with the jihadis' hands and stand against the Shiite campaign," he said. Al-Adnani added a warning that "the gates of hell have opened" and that the Islamic State of Iraq "will carry out more attacks in the near future by suicide bombers, car bombs and roadside bombs." He specifically threatened that the group will track down Shiite judges and investigators. The series of explosions and shootings Thursday killed at least 44 people and wounded more than 200 in Baghdad and elsewhere, police said. The country has seen more coordinated attacks since U.S. troops withdrew from Iraq at the end of 2011, the official said. An Iraqi government spokesman declined comment Thursday. The U.S. Embassy in Baghdad said it "strongly condemns" the terrorist attacks. "These heinous acts targeted people going to work and shopping, children going to school and security forces working to protect the citizenry," the embassy said, adding the attacks were "targeted at all the people of Iraq in a desperate effort to undermine Iraqi society and its institutions." The United Nations' Assistance Mission in Iraq also condemned the violence "in the strongest possible terms." "The continuing violent attacks on Iraqis are totally unacceptable and have to stop," said Martin Kobler, special representative of the U.N. secretary-general, in a statement. The attacks "are meant to hinder the achievement of national unity and stability," he said.