A new wave of car bombs struck the Iraqi capital city of Baghdad and northern Iraq on Sunday, killing 56 people and wounding some 152, police said. The worst violence in the day started in Baghdad in the morning, when at least eight car bombs ripped through commercial areas, killing a total of 32 people and wounding 94, in seven of Baghdad\' s Shiite-majority districts. In one of the attacks, a car bomb went off at a popular market in Sabie al-Bour district, in the northern part of Baghdad, killing up to six people and wounding 18 others, a police source told Xinhua on condition of anonymity. Later on, another car bomb was detonated at a marketplace and a nearby parking lot in al-Huriyah district in northeastern Baghdad, killing two people and wounding 10 others, the source said. Meanwhile, a car bomb exploded at a marketplace in Mashtal district in eastern Baghdad, leaving four people killed and seven wounded, while a fourth car bomb struck a popular market at Shaab district in the northeastern part of the capital, killing four people and wounding 17, the source added. A car bomb hit Abu Dsheer district in southern Baghdad and killed at least six people and wounded 14 others, and another car bomb went off at a thoroughfare in Baghdad\'s southern district of Baiyaa, killing five people and wounding 11, the source said. Two more car bombs were detonated in a quick succession at a crowded market in the southeastern suburb of Nahrawan, killing at least five people and wounding 17, he added. In the meantime, up to 14 people were killed and 55 wounded when a suicide bomber blew up his explosive-laden car near dozens of soldiers and retired military officers who were gathering to collect their salaries from a government- owned bank in eastern the city of Mosul, some 400 km north of Baghdad, a provincial police source anonymously told Xinhua. \"The deaths were three soldiers and 11 civilians, and the wounded were nine soldiers and 46 civilians,\" the source said, adding that the civilians were retired officers, bank employees and customers. In a separate incident, three soldiers were killed and another was wounded in a roadside bomb explosion near their patrol in al- Rashidiyah area in northern the city, the source said. Also in Mosul, unidentified armed men shot dead two construction workers in eastern the city, the source said without giving further details. Elsewhere, gunmen attacked a house in a village near the city of Dowr, some 150 km north of Baghdad, and shot dead a member of a government- backed Sahwa paramilitary group, his son and his nephew before they fled the scene, a local police source said. In the same area, another Sahwa group member was wounded in a roadside bomb attack, the source added. The Sahwa militia, also known as the Awakening Council or the Sons of Iraq, consists of armed groups, including some powerful anti-U.S. Sunni insurgent groups, who turned their rifles against the al-Qaida network after Sahwa\'s leaders became dismayed by al- Qaida\'s brutality and religious zealotry in the country. Separately, unidentified gunmen blew up seven under construction houses belonging to police and army officers in west of the city of Tikrit, some 170 km north of Baghdad, a local police source said. In Iraq\'s eastern province of Diyala, two farmers were shot dead by gunmen at a village near the town of Abu Saiyda, some 30 km northeast of the provincial capital city of Baquba, which is about 65 km northeast of Baghdad, a provincial police source anonymously told Xinhua. Meanwhile, a policeman was wounded in a roadside bomb blast near his patrol in the western part of Baquba, the source said. No group has so far claimed responsibility for the attacks, but the al-Qaida front in Iraq, in most cases, was responsible for such massive attacks, raising fears that the terrorist group and other militia could return to widespread violence. Observers see that the security situation in Iraq began to deteriorate on April 23 after the security forces cracked down on a Sunni Arab protest camp in Iraq\'s northern city of Hawijah. The clampdown sparked fierce clashes across the country\'s predominantly Sunni provinces between the Sunni tribes and the security forces. Overall levels of violence by insurgent groups have since escalated and become audacious, as waves of massive bombings and almost daily attacks left thousands of Iraqis killed and wounded. Iraq is witnessing its worst eruption of violence in recent years, which raises fears that the country is sliding back to the full-blown civil conflict that peaked in 2006 and 2007, when monthly death toll sometimes exceeded 3,000. The UN Assistance Mission for Iraq has said that almost 6,000 civilians were killed and over 14,000 others injured in Iraq from January to September this year.