A man runs after a car bomb blast Friday in Abu Dshir in Baghdad. The attack was one of numerous bombings and shootings around the country in which 24 people were killed and 45 injured.

Baghdad ? A car bomb exploded in a market in southern Baghdad late Friday afternoon, killing at least 14 people and prompting an outburst of sectarian rioting, according to police and witnesses.

The attack was one of numerous bombings and shootings around the country in which 24 people were killed and 45 injured. They illustrated the tenuousness of the security situation in Iraq, where violence has fallen to four-year lows in recent months but political and sectarian divisions can quickly lead to bloodshed.

The bomb in a red Daewoo sedan blew up in the Abu Dsheer neighborhood, a Shiite enclave in the largely Sunni area of Dora, according to Iraqi security officials. The district had been a hotbed of insurgency before U.S. troops engaged in major combat there last year during the buildup of forces.

The U.S. military now considers parts of Dora safe enough to begin removing the giant blast barriers installed around the city as part of its counterinsurgency strategy to control the population and forestall attacks.

But the melee that broke out Friday afternoon showed how easily ethnic tensions can flare.

The bomb blew up about 4:30 p.m. as shoppers were crowding an outdoor market, officials said. As residents began removing the bodies, national police arrived from a largely Sunni unit recently assigned to the area, witnesses said. The officers began firing their rifles in the air, apparently to clear away bystanders, they added.

Residents began hurling bricks at the police and setting tires ablaze, sending columns of black smoke into the air, according to the witnesses. Some protesters yelled slogans against Iraq’s Shiite-led government and in support of Moqtada al-Sadr, a firebrand Shiite cleric known for his anti-American rhetoric, they said.

“The people were accusing them (police) of not protecting the neighborhood, and helping the insurgents,” said a college student from the neighborhood, Hassan al-Obeidi.

Three of the demonstrators were wounded by bullets, according to witnesses. U.S. military and Iraqi security forces cordoned off the area with armored vehicles, warning residents to stay inside, as American helicopters swept overhead.

Conflict between Sunnis and Shiites raged in central Iraq from 2005 to 2007, even as insurgents from both groups targeted U.S. forces. The violence has plummeted in recent months thanks to U.S. counterinsurgency efforts, a cease-fire declared by al-Sadr, and the decision of largely Sunni armed groups to switch allegiances and become U.S. allies.

But smoldering resentment remains.

On Friday morning, hundreds of people took part in a funeral procession in Baghdad’s sprawling Sadr City slum for a parliamentary deputy from al-Sadr’s bloc targeted in a bombing a day earlier. U.S. authorities in Iraq condemned the killing, which they attributed to unidentified Shiite extremists.