Wave of carnage rips across Iraq Grim aftermath: Iraqi men gather at the scene of one of two car bombs that exploded in Baghdad's Habibiyah area. A co-ordinated wave of car bombings has torn through mostly Shiite areas of Baghdad, killing at least 66 people and maiming nearly 200 as insurgents step up the bloodshed roiling Iraq. The attacks in markets and other areas frequented by civilians on Monday are the latest sign of a rapid deterioration in security as sectarian tensions are exacerbated by anti-government protests and the war in Syria grinds on. Most of the killings came over the past two weeks in the most sustained violence since US troops left in December 2011. The group, known as the Islamic State of Iraq, frequently uses car bombs and co-ordinated blasts against Shiites to undermine Iraqis' confidence in the Shiite-led government. The day's deadliest attack happened when two bombs exploded in the eastern Habibiya area on the edge of the Shiite district of Sadr City. Twin blasts also struck an open-air market in the predominantly Shiite al-Maalif area, killing six and wounding 12. Another car bomb exploded in Sadoun Street in downtown Baghdad. Among the wounded were four policemen at a nearby checkpoint. The central street is one of the capital's main commercial areas and lined with clinics, pharmacies and shops. "What crime have those innocent people committed?" said witness Zein al-Abidin. Who is responsible for these massacres? The surge in violence is widely considered to have begun after government forces opened fire on a Sunni protest camp in the town of Hawija in April, killing about 45 people. Since then, Sunnis have struck back in predominantly Shiite areas. "They transformed the political crisis into a series of local conflicts in the Sunni-populated provinces," Iraq analyst Maria Fantappie of the International Crisis Group said. As it stands, the risk is a metastasis of armed clashes across these provinces. Monday last week, when a wave of attacks killed 113 people in Shiite and Sunni areas, was the deadliest day in Iraq since July 23, when attacks aimed largely at security forces killed 115. On Sunday, the Iraqi army started operations against al-Qaeda in Mesopotamia, the home-grown terrorist group, and other armed groups in Anbar province, officials said, where predominantly Sunni protests have flared against the mostly Shiite government.