BAGHDAD (AP) — A wave of car bombings and other attacks in Iraq killed at least 58 people in mostly Shiite-majority cities on Sunday, another bloody reminder of the government’s failure to stem the surge of violence that is feeding sectarian tensions.

Iraq is experiencing its deadliest bout of violence since 2008, raising fears the country is returning to a period of widespread killing such as that which pushed it to the brink of civil war following the 2003 U.S.-led invasion. More than 4,000 people have been killed in attacks since the start of April, including 804 just in August, according to United Nations figures.

Sunday’s deadliest attack was in the city of Hillah, 95 kilometers (60 miles) south of Baghdad, where a car bomb near an outdoor market killed nine civilians and wounded 15 others, a police officer said. A few minutes later, another car bomb went off nearby, killing six civilians and wounding 14, he added.

In the nearby town of Iskandariyah, 50 kilometers (30 miles) south of the capital, another car bomb hit a parking lot, killing four civilians and wounding nine, police said.

Another car bomb went off in an industrial area of the Shiite city of Karbala, killing five and wounding 25, a police officer said. Karbala is 80 kilometers (50 miles) south of Baghdad. In the aftermath, security officials inspected burnt-out cars in front of what appeared to be a smashed row of workshops.

In Kut, another Shiite-dominated city 160 kilometers (100 miles) southeast of Baghdad, a car bomb targeted construction workers and food stalls, killing two and wounding 14, another provincial police officer said.

Seven more civilians were killed and 31 others were wounded when four separate car bombs ripped through the towns of Suwayrah and Hafriyah outside Kut, police said.

In Baghdad’s northern Sunni-dominated Azamiyah neighborhood, a car bomb that exploded near the convoy of the head of Baghdad’s provincial council killed three and wounded eight, police say. The council head escaped unharmed.

Two other car bombs hit the southern cities of Basra and Nasiriyah, killing eight civilians and wounding 26, two police officers said. And two more civilians were killed when a bomb hit a police patrol in Baghdad’s Sunni western suburb of Abu Ghraib. Nine other people were wounded.

To the northeast of Baghdad, gunmen broke into a farm in the village of Abu Sayda and killed three Sunni farmers, police said

No one has claimed responsibility for the blasts, which targeted commercial areas and parking lots in seven cities. But systematically organized waves of bombings are often used by al-Qaida’s local branch, known as the Islamic State of Iraq, to undermine confidence in the Shiite-led government.

Sometimes insurgents launch multiple attacks for two or more days in a row. On Saturday, 27 people were killed in suicide attacks, bombings and shootings.

In the afternoon, police found the bodies of four Sunni men killed with gunshots to the head. The men, all relatives, were kidnapped early Sunday by gunmen who stormed their house in Baghdad’s southern Youssifiyah suburb.

Police and hospital officials also said that a car bomb exploded at night in a commercial street in Baghdad’s eastern neighborhood of Mashtal, killing five people and wounding 15 others.

Medical officials confirmed the casualty figures for all the attacks. All spoke anonymously as they weren’t authorized to release information.