BAGHDAD - A car bomb ripped through a crowded market in southern Iraq on Wednesday, killing at least 32 people, and wounding 70, officials said.

Police locked down Al-Bathaa, a Shi'ite Muslim town 30 km (20 miles) west of Nassariya that has seen little violence, while hospital officials appealed for assistance from neighboring cities to help them cope with the wounded.

Colonel Aziz al-Atabi, media director for the Iraqi army's 10th division, said 32 people had been killed and 70 wounded.

Pictures posted online by local journalists showed the charred wreck of a car the bomb was planted in, burned body parts and bloodstained rags among vegetables strewn on the floor.

High school teacher Hussein Salim said the market was supposed to be guarded by the police. He said he rushed to the scene and helped gather body parts, some of which had been blown onto the roof of nearby homes.

How could the car enter the market? It was crowded with people ... The police neglected their job, he said. I saw five children and six women among the dead.

Angry locals protested when the area's police chief and governor arrived on the scene, Salim said. This prompted the governor's bodyguards to open fire though it was it was unclear if the shots were aimed at the crowd or in the air.

Residents said U.S. military helicopters hovered overhead after the blast.

The sectarian bloodshed and insurgency unleashed by the 2003 U.S.-led invasion has fallen sharply across Iraq since its peak in 2006/07, and the Shi'ite Muslim south has tended to be one of the quietest areas.

But insurgents, including Sunni Islamist al Qaeda, who view Shi'ites as heretics, continue to carry out devastating car and suicide bomb attacks.

Analysts say violence is likely to rise ahead of parliamentary elections next January, which will pit not just Shi'ite parties against once dominant Sunnis and minority Kurds, but also against rival Shi'ite groups.

The withdrawal from Iraqi city centers by U.S. combat troops at the end of the month is another potential trigger point for an increase in attacks, Iraqi officials say.

(Additional reporting by Aseel Kami and Waleed Ibrahim; Writing by Michael Christie; Editing by Richard Balmforth)