A car bomb shattered a convoy of Westerners in Baghdad (search) Monday, killing at least 13 people, including three General Electric workers and two bodyguards. Crowds rejoiced over the attack, dancing around a charred body and shouting "Down with the USA!"

The blast, during the morning rush hour near busy Tahrir Square (search), was the second vehicle bombing in Baghdad in as many days amid an upsurge of bloodshed in the capital only two weeks before the formal end of the U.S.-led occupation.

Iraq's interior minister said he believed foreigners carried out the attack, and Prime Minister Iyad Allawi (search) accused Jordanian-born terrorist Abu Musab al-Zarqawi of trying to disrupt the transfer of sovereignty. Al-Zarqawi, believed to have contacts with Al Qaeda, is accused in last month's decapitation of American Nicholas Berg (search).

The chaotic scene Monday was reminiscent of the violence and anti-American hatred that accompanied the March 31 slaying in Fallujah of four Americans, whose bodies were mutilated and hung from a Euphrates river bridge.

Moments after the thunderous blast, which shook the heart of the capital, young men raced into the street, hurling stones at the flaming wreckage, looting personal belongings of the victims and chanting slogans against the occupation.

Iraqi police stood by helplessly — unable to control the crowd only weeks before they are to assume more security responsibility under the U.S. exit strategy.

As flames and smoke enveloped the vehicles, youths taunted American troops and threatened Western journalists. American troops beat one man with a stick, but after failing to restrain the crowd, the troops and police withdrew.

Crowds chanted "Down with the USA!" and set fire to an American flag. Young men gleefully displayed a British passport and identification card issued by the Coalition Provisional Authority.

As the police left, the crowd poured kerosene into one of the vehicles and set it on fire. Heavy, black smoke poured from the vehicle. About 20 youths danced around a charred body.

The dead included three employees of Granite Services Inc., a wholly owned, Tampa, Fla.-based subsidiary of General Electric Co., and two security contractors employed by Olive Security of London. The Westerners included one American, two Britons, one Frenchman and one victim of undetermined nationality, officials said.

U.S. officials said 62 people were injured, including 10 foreign contractors. Hospital officials said many of the wounded had lost limbs.

The foreign victims were helping to rebuild power plants, Allawi said.

The attack was the latest in a series directed against Iraq's infrastructure or those seeking to rebuild it after decades of war, international sanctions and Saddam Hussein's tyranny.

GE said Monday it has no plans to pull its workers out of the country.

"We remain committed to the reconstruction of Iraq," said GE spokeswoman Louise Binns.

Nevertheless, the bombing dramatizes the dangerous challenge the United States faces as it struggles to revive the country's power supply and show Iraqis the occupation can improve their lives.

The attacks have sent contractors scurrying from Iraq. They've slowed improvements and caused the U.S.-led coalition to fall short of its goal of delivering 6,000 megawatts of consistent power in June. Power generation currently hovers at about prewar levels of 4,400 megawatts.

Before the war, Baghdad residents enjoyed about 20 hours of electricity a day. Baghdad's problem is that American authorities redistributed electricity evenly across the country — everybody now gets 8-12 hours a day.

U.S. officials said they were uncertain whether the bomb was detonated by a homicide attacker.

A policeman, Ghahtan Abood, said the bomb went off when a vehicle rammed the contractors' three-vehicle convoy as it sped down the street. However, coalition officials said they were unsure of the account and that the bomb may have been planted along the street and detonated as the convoy passed.

An Interior Ministry official said 13 people were killed in the blast, including the five foreigners.

The bomb exploded as three SUVs carrying the contractors were passing through the square. The blast destroyed eight vehicles and turned nearby shops and a two-story house to rubble.

Terrified and dazed survivors scrambled to pull victims from the wreckage. One elderly man, pale and semiconscious, was carried away in his blood-soaked nightclothes.

Iraqi bystanders scooped up victims and loaded them into vehicles or pickup trucks to speed them to hospitals. Body parts and fragments of clothing lay scattered around the street.

Even some of the wounded were angry at the Americans.

"Maybe the Americans have done this to us to allow them to stay on longer," Qais Alwan said from his hospital bed. "OK, let them stay, but why are they doing this to us? All the victims are Iraqis, so by God, they must be Americans because Iraqis don't kill fellow Iraqi brothers."

But Allawi, the prime minister, implicated al-Zarqawi, who has also been accused of the 2002 assassination of an American diplomat in Jordan.

"Al-Zarqawi and his followers are earnestly working to prevent the success of this measure," Allawi said. "I want our people to be patient this month against those forces that are trying to assault them, and I promise the people that we are going to get rid of them and victory will be ours to build a free and decent Iraq life."

Allawi, who was close to the CIA and State Department during his years in exile, said his government was preparing tough measures to deal with the violence. He offered no details.

In other violence Monday, a roadside bomb struck an Army convoy of 20-vehicles about three miles north of Fallujah, witnesses said. It could not be immediately determined if there were any casualties.

Near the town of Salman Pak southeast of Baghdad, police said a car bomb exploded between police vehicles, killing four people and wounding four. The report could not be independently confirmed.

In Mosul, four members of the Iraqi Civil Defense Corps were wounded when a bomb exploded as they were patrolling near a U.S. base.

In Kut, authorities said attackers hurled two grenades at an American patrol. One Iraq on a motorcycle was wounded in the crossfire, witnesses said.