BAGHDAD - A suicide car bomber sent a fireball through a crowded market yesterday in the Shiite holy city of Kufa, killing at least 16 people and threatening to further stoke sectarian tensions in relatively peaceful areas south of Baghdad.

The bomb was detonated in a gray sedan beside a restaurant and across the street from a girls' primary school.

Before the explosion, the attacker was seen driving slowly as he searched for a place to park on the narrow street, which was lined with carts, witnesses said. The car was packed with about 550 pounds of explosives, police said.

A mob immediately gathered at the grisly scene, surrounding the blast's crater and blaming U.S. forces and the Iraqi police for allowing the attack.

Kufa, 100 miles south of Baghdad, is a stronghold of the Mahdi Army militia, which is loyal to radical Shiite cleric Muqtada al-Sadr. U.S. officials have expressed fears that Sunni insurgents led by al-Qaeda are carefully picking their targets to provoke retaliatory violence to derail efforts to stabilize the country.

Protesters at the bombed site were joined by members of Sadr's Mahdi Army. They blocked the police and security forces from entering the area, and three responding ambulances were destroyed. Many of the injured eventually were piled into pickup trucks for the trip to hospitals.

The blast sent flames through a nearby two-story kebab restaurant, charring the interior. Angry residents demanded better protection and accused authorities of fortifying their own homes and offices at the expense of the public.

"They do not care about the fate of the poor," said Laith Hussein, 29, who helped carry some of the wounded to the hospital. "We demand real, effective security measures to protect us."

The predominantly Shiite southern areas have seen a spike in violence and unrest, blamed in part on militants who have fled a security crackdown in Baghdad. The U.S.-led offensive is intended to curb violence and allow the Shiite-led government some breathing room to implement reforms, including proposals to empower minority Sunni Arabs and help end the insurgency. There has been little evidence, though, of any movement toward those goals.

Still, Sunni Vice President Tariq al-Hashimi appeared to back away from a threat to lead a walkout from the government.

"I can say that we can, God willing, build an ambitious future based on a real partnership and joint understanding," Hashimi told reporters Monday after a late-night meeting with Prime Minister Nouri al-Maliki, a Shiite. "And I think it is very important to go ahead with the political project."

Hashimi said the meeting was an effort to "melt the ice."

Ali Baban, the Sunni planning minister, reaffirmed that the Sunni bloc had no plans to quit the government.

At least 68 people were killed or found dead nationwide yesterday, more than half of them apparent victims of so-called sectarian death squads usually run by the Shiite militias. Twenty-five bullet-riddled bodies were found in Baghdad, all but five on the predominantly Sunni western side of the Tigris River, where sectarian violence appears to be on the rise.

A roadside bomb killed two U.S. soldiers and wounded another in southeast of Baghdad, the military said.

Residents in Baqubah, a volatile city northeast of Baghdad, said that a U.S. helicopter opened fire on an elementary school, killing seven students and wounding three. A U.S. spokesman, Lt. Col. Christopher Garver, said the military was investigating the reports.

Cheney Seeks Help From Arab Leaders

Vice President Cheney is reaching out to moderate Arab leaders for help in bringing stability to Iraq,

a mission that will include pleas for postwar support for Iraq's minority Sunnis.

He departed yesterday

on a weeklong mission to the Middle East, right after a visit to the region by Secretary of State Condoleezza Rice.

Explaining the trip, White House press secretary

Tony Snow said Cheney was able to deal with leaders in the region "on

a basis of personal trust and confidence that I

think gives him special valuein trying to talk about ways forward."

But some Mideast experts outside the administration suggested that Cheney's visit also might be an attempt to try to clear up what might be viewed by some leaders in

the region as mixed messages from Rice.

"Some of these people wonder if Condi Rice really speaks for the president when she decides she's going to talk to the Syrians, or when she agrees to go to a conference that includes the Iranians,"

said David Mack, a

retired diplomat.

- Associated PressEndText