A Plague on the Nation

Gunmen also ambushed a bus in the predominantly Sunni neighborhood of Amariyah in western Baghdad, killing six passengers, including a woman, and the driver, police Capt. Jamil Hussein said.

On Sunday, masked Shiite gunmen roamed Baghdad's Jihad neighborhood, dragging Sunnis from their cars, picking them out on the street and killing them in a brazen series of attacks. Police said 41 people were killed, although there were conflicting figures that put the death toll at more than 50 and as low as nine.

Sunni leaders expressed outrage over the killings, and President Jalal Talabani, a Kurd, appealed for calm, warning that the nation stood "in front of a dangerous precipice."

Ayad al-Samaraie, a member of the Iraqi Accordance Front, the largest Sunni bloc in parliament, blamed members of radical Shiite cleric Muqtada al-Sadr's Mahdi Army militia for Sunday's killings. He called on the U.N. Security Council to send peacekeepers to Iraq, saying Monday that U.S.-led "occupation forces" cannot protect Iraqis.

The head of the bloc Adnan al-Dulaimi also urged the Shiite-led government to stop the militias from carrying out violence. "The gangs want to pave the way for sectarian strife," he said. "The attacking of Sunnis in Jihad and other places in Baghdad is aimed at weakening the Sunnis and driving them from Baghdad."

U.S. military spokesman Maj. Gen. William Caldwell said American troops responded to the area only after being called by their Iraqi counterparts and found 14 Iraqis killed.

He said a conscious decision had been made to crack down on militias that are blamed for much of the sectarian violence in the country, but he declined to single out any groups.

"The civilians clearly are taking a heavy hit at the activities of these illegal armed groups through murder, intimidation, kidnappings and everything else and those are the groups that we're going after," he said.

Monday's violence began when a car parked near a repair shop on the edge of the Shiite slum of Sadr City blew up, followed within minutes by a suicide car bomber who drove into the crowd that had gathered near the site.

Hospital officials said at least eight people were killed and 41 wounded in the blast. AP Television News footage showed the devastated repair shop with a crumpled roof and the blackened hulks of cars on the street outside.

A bomb also exploded in the Shurja market in central Baghdad, killing three people and wounding 18, police Col. Adnan al-Obeidi said.

In Kirkuk, a suicide truck bomber struck an office of one of the main Kurdish political parties in Iraq, the Patriotic Union of Kurdistan, killing five people and wounding 12, police said.

The streets in the religiously mixed Baghdad neighborhood of Jihad, meanwhile, were relatively calm on Monday, although three people were wounded in a mortar barrage, police said, a day after the deadly rampage by Shiite gunmen.

Al-Sadr denied responsibility for the attacks Sunday and called on both Shiites and Sunnis to "join hands for the sake of Iraq's independence and stability." He assured Vice President Tariq al-Hashimi, leader of the largest Sunni Arab party, that he would punish any of his militiamen if they were involved.

The surge in violence was likely to further inflame Shiite-Sunni tensions and undermine public confidence in the new unity government. It also raised new questions about the effectiveness of the Iraqi police and army to curb such attacks.

Several carloads of gunmen drove into the Jihad area, stopping cars, checking passengers' ID cards and shooting to death those with Sunni names. Residents contacted by telephone told of gunmen systematically rounding up and massacring Sunni men.

A Shiite shopkeeper said he saw heavily armed men pull four people out of a car, blindfold them and force them to stand to the side while they grabbed five others out of a minivan.

After about 10 minutes, the gunmen took the nine people to a place a few yards away from the market and opened fire on them, Saad Jawad al-Azzawi said.

Prime Minister Nouri al-Maliki, a Shiite, has promised to disband Shiite militias and other armed groups, which are blamed for much of the sectarian violence, but they have flourished in large part because of the inability of Iraqi and coalition forces to guarantee security.

In other violence Monday, according to police:

•A police patrol in the southern city of Hillah hit a roadside bomb, leaving one policeman dead and four wounded.

•Clashes broke out between Interior Ministry commandos and gunmen in the insurgent stronghold of Dora in southern Baghdad, leaving one commando dead and two wounded.

•A bomb struck a gas station in Mahmoudiya, south of Baghdad, wounding 10 people.

•Gunmen killed the preacher at a Sunni mosque and a Kurdish university employee in separate attacks in the northern city of Mosul.

•A former high-ranking officer from Saddam Hussein's army, ex-staff Maj. Gen. Salih Mohammed Salih, was killed in a shootout in the southern city of Basra.

•A member of the provincial council in volatile Diyala, Adnan Iskandar al-Mahdawi, was killed and two of his guards were wounded in a drive-by shooting.