Dozens of people died as US forces fought insurgents loyal to the militant Shia cleric Muqtada Sadr today in the Baghdad slum of Sadr City.
At least one US soldier was among the 34 victims, said US and Iraqi authorities, and 193 people were injured.
Elsewhere in Baghdad, a roadside bomb explosion targeted the governor's convoy, killing two people, the Interior Ministry said. Ali Haidri escaped injury but three of his bodyguards were hurt in the attack today in the western neighborhood of Hay al-Adel.
The fighting in Sadr City erupted when militants attacked US forces carrying out routine patrols, said US Army Capt. Brian O'Malley.
O'Malley said the American soldier was killed by small arms fire and that several others were wounded. Residents said loud explosions and gunfire could be heard across Sadr City on Monday night and that clashes spilled over into Tuesday morning.
The renewed fighting came after a period of calm in the impoverished neighborhood after Sadr called on his followers last week to observe a cease-fire and announced that he planned to enter politics.
But Sadr aides later said peace talks in Sadr City between the cleric's representatives and interim Prime Minister Ayad Allawi's government had stalled, with the government refusing militant demands for American troops to keep out of the troubled district.
Government officials have since said they are not involved in any negotiations with Sadr's militia. The Americans have said they never took part in any talks.
Sadr led a three-week uprising in the holy city of Najaf that ended 10 days ago with a peace deal that allowed his Mahdi militia fighters to walk away with their guns. The combat in Najaf left thousands dead and devastated much of the city.
Many Mahdi militiamen are believed to have returned to their stronghold in Sadr City.
In the attack on the Baghdad governor, gunmen opened fire on al-Haidri's convoy seconds before the explosion, hoping to direct the vehicles toward the blast, Rahman said.
Three of his bodyguards were hurt in the attack in the western Baghdad neighborhood of Hay al-Adel, al-Haidri said.
"The people behind this attack want to hurt Iraq and to hinder the progress in this country," al-Haidri said.
The governor's BMW appeared intact, but a car next to it was totally burned. The bomb made a small crater in the pavement and the street. One person was sprawled out in the street. Police blocked the area and prevented people from getting close to the cars.
Tuesday's violence came a day after a suicide attack on a military convoy outside Fallujah killed seven US Marines and three Iraqi soldiers, US military officials said. It was the deadliest day for American forces in four months.
The force of the blast on a dusty stretch of wasteland nine miles north of Fallujah, a hotbed of Sunni insurgents, wrecked two Humvee vehicles and hurled the suicide car's engine far from the site, witnesses said.
The bombing underscored the challenges US commanders face in securing Fallujah and surrounding Anbar province, the heartland of a Sunni Muslim insurgency bent on driving coalition forces from the country.
US forces have not patrolled in Fallujah since ending a three-week siege of the city in April that had been aimed at rooting out militiaman. Insurgents have only strengthened their hold on Fallujah since then.
Early Tuesday, Fallujah residents reported strong explosions, but the US command said it had no information.
Elsewhere, one American soldier was killed and another wounded during an attack on a convoy near the Iraqi capital, the US military said Tuesday. The convoy came under attack from an improvised explosive device at around 11:45 p.m Monday, the military said in a statement.
With Monday and Tuesday's deaths, 992 US service members have died since the beginning of military operations in Iraq in March 2003, according to a count by The Associated Press based on Defense Department figures.
The military condemned the Fallujah bombing as "a desperate act of inhumanity" but insisted American troops will stay the course in Iraq until local forces are in a position to take over security operations. The slain Americans belonged to the 1st Marine Expeditionary Force.
Hours after the attack, an unmanned US spy plane crashed in Fallujah. Afterward, jubilant residents picked up pieces of debris and danced in the streets, displaying pieces of the aircraft to reporters, witnesses said.
Since the Marine siege ended, gunmen have been using the city a base to manufacture car bombs and launch attacks on US and Iraqi government forces. Fallujah has become a no-go zone for US troops, though American warplanes have repeatedly carried out airstrikes against alleged militant safe houses there.
The car bombing resulted in the largest number of Americans killed in combat in a single day since May 2, when nine US troops died in separate mortar attacks and roadside bombings in Baghdad, Ramadi and Kirkuk.
Seven troops were killed on two days last month, but in each case, there were six Americans and one foreign coalition member who died. On Aug. 21, six US service members and one Polish soldier died in combat, and six were killed on Aug. 15, along with a Ukrainian soldier.