Baghdad • A coordinated wave of car bombings tore through mostly Shiite areas of Baghdad on Monday, 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 are the latest sign of a rapid deterioration in security as sectarian tensions are exacerbated by anti-government protests and the war in neighboring Syria grinds on.
More than 450 people have been killed across Iraq in May. Most of the killings came over the past two weeks in the most sustained wave of violence since U.S. troops left in December 2011.
The surge in attacks is reminiscent of the sectarian carnage that pushed Iraq to the brink of civil war in 2006 and 2007. April was Iraq's deadliest month since June 2008, according to a United Nations tally that put last month's death toll at more than 700.
There was no immediate claim of responsibility for Monday's bombings, but they bore the hallmarks of al-Qaida's Iraqi arm. The group, known as the Islamic State of Iraq, frequently uses car bombs and coordinated 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 sprawling Shiite district of Sadr City. Those blasts killed 12 and wounded 35, police said.
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 the busy commercial Sadoun Street in downtown Baghdad. It killed five civilians and wounded 14, police said. Among the wounded were four policemen who were at a nearby checkpoint.
The central street is one of the capital's main commercial areas and is lined with clinics, pharmacies and shops. Firefighters were seen struggling to extinguish flames as police sealed off the area. Several shops were partially damaged or burned.
''What crime have those innocent people committed?" asked witness Zein al-Abidin. "Who is responsible for these massacres?"
Elsewhere across the bloodied capital city, police reported:
A car bomb went off in the eastern New Baghdad area as officers were waiting for explosives experts to dismantle it. A civilian was killed and nine others wounded.
In the north, a blast in the Sabi al-Boor neighborhood killed eight civilians and wounded 26. In the Kazimiyah district, a car bomb blew up near a bus and taxi stop, killing four and wounding 11.
Another blast killed four and wounded nine in the Shaab area. And an attack in the Hurriyah neighborhood left five dead and 14 wounded.
A bomb in the southwestern neighborhood of Bayaa killed six civilians and wounded 16.
In Baghdad's central Sadria area, a car bomb killed three civilians and wounded 11.
In the east, a blast killed five and wounded 12 in the Jisr Diyala area. Car bombs also struck the Baladiyat neighborhood, killing four and wounding 11.
And in Madain, about 12 miles south of central Baghdad, a car bomb killed three and wounded nine.
Medical officials confirmed the causality figures. All officials spoke on condition of anonymity because they were not authorized to release information.
The day's bloodshed was the deadliest since last Monday, when a wave of attacks killed 113 people in Shiite and Sunni areas. That was the deadliest single day in Iraq since July 23, when attacks aimed largely at security forces killed 115.
The U.S. Embassy issued a statement condemning the latest attacks.
Although violence has decreased sharply since the height of the insurgency that followed the 2003 U.S.-led invasion, militants are still capable of carrying out lethal attacks nationwide. The recent wave of attacks has raised tensions between the country's Sunni minority and Shiite-led government.
Since late December, members of Iraq's Sunni community have been protesting against the government. They cite a range of grievances, including poor services, discrimination and the application of tough anti-terrorism policies they believe unfairly target their sect.
The unrest is fueling long-simmering sectarian rifts in the country that only grew more divisive after an April 23 crackdown by security forces on a Sunni protest camp. The crackdown in the town of Hawija left many protesters dead.
Maria Fantappie, an Iraq analyst at the International Crisis Group, linked the uptick in violence to the protests and said the events at Hawija marked a turning point.
"They transformed the political crisis into a series of local conflicts in the Sunni-populated provinces," she said. "As it stands, the risk is a metastasis of armed clashes across these provinces."
She said outright civil war between the protesters who remain divided over their support for violence and security forces loyal to the Shiite-led government is unlikely, however.
Alarmed by a nationwide deterioration in the security situation, Iraqi Prime Minister Nouri al-Maliki recently ordered a reshuffle in senior military ranks.
Authorities have also launched a military operation in the country's western Anbar province to chase down fighters from al-Qaida in Iraq.
The group is growing stronger as a result of rising lawlessness on the Syrian-Iraq frontier and cross-border cooperation with the Syrian militant group Jabhat al-Nusra, or the Nusra Front, a rebel faction fighting to oust President Bashar Assad.