Baghdad, Iraq ? A spike in fighting with Sunni and Shiite insurgents killed eight Americans Tuesday and early today in the Baghdad area, pushing the U.S military count to 1,003.

The grim milestone was surpassed after a surge in fighting, which has killed 17 U.S. service members in the past four days. A soldier was killed early today in when a roadside bomb struck a convoy near Balad, 35 miles northeast of Baghdad. Two soldiers died in clashes Tuesday with militiamen loyal to rebel Shiite cleric Muqtada al-Sadr. Five other Americans died Tuesday in separate attacks, mostly in the Baghdad area. Seven Marines were killed Monday in a suicide car bombing north of Fallujah. Two soldiers were killed in a mortar attack Sunday.

West of the capital, U.S. warplanes swooped low Tuesday over Fallujah in airstrikes after the Marines and three Iraqi soldiers were killed in the car-bombing near the Sunni insurgent-controlled city.

A group linked to Jordanian-born militant Abu Musab al-Zarqawi — Tawhid and Jihad — posted a statement on a militant Web site claiming responsibility for the attack, describing it as “a martyr operation … that targeted American soldiers and their mercenary apostate collaborators from the Iraqi army.”

Fighting between U.S. soldiers and al-Sadr’s militiamen erupted Tuesday when U.S. officials said the cleric’s gunmen fired on Americans carrying out patrols in the Sadr City district of Baghdad. Two Americans died in the fighting, U.S. officials said.

A senior Iraqi Health Ministry official, Saad al-Amili, said 35 Iraqis were killed and 203 wounded in the Sadr City clashes. An al-Sadr spokesman, Sheik Raed al-Kadhimi, blamed “intrusive” American patrolling for provoking the fighting.

“Our fighters have no choice but to return fire and to face the U.S. forces and helicopters pounding our houses,” al-Kadhimi said in a statement.

A destroyed vehicle is shown at the site of a massive car bomb attack on the outskirts of Fallujah, northwest of Baghdad, Iraq. Seven U.S. Marines and three Iraqi National Guard soldiers died in the attack Monday, U.S. military officials said. In retaliation, U.S. forces launched airstrikes Tuesday in Fallujah.

Late Tuesday, the militia announced a unilateral cease-fire but said it would fight back in self defense. It was unclear whether the statement had any meaning since the militia routinely defends its actions as legitimate self defense.

U.S. Army Capt. Brian O’Malley said he was unaware of the cease-fire offer but that the area was quiet in the early evening. “We only fire when we are fired at, but we will not stop our patrols or withdraw from our positions,” he said.

At the Pentagon, Gen. Richard Myers, chairman of the Joint Chiefs of Staff, blamed the spike in U.S. combat deaths on an insurgency that “is becoming more sophisticated in its efforts to destabilize the country.”

“We are aggressively seeking and capturing those insurgents who are not willing to do so themselves, but are encouraging people to commit suicide attacks,” Myers told reporters Tuesday.

Battle in Sadr City

During the Sadr City fighting, U.S. warplanes flew over the sprawling neighborhood — home to some 2 million people. American tanks, their turrets spinning, deployed in key intersections. Ambulances with sirens wailing rushed the wounded to hospitals as plumes of heavy, black smoke rose over the mainly Shiite neighborhood.

U.S. forces appeared to be carrying out most — if not all — of the fighting.

Elsewhere, a bomb exploded Tuesday near the convoy of the governor of the Baghdad region, killing two people. Gov. Ali al-Haidri escaped injury, Interior Ministry spokesman Col. Adnan Abdel Rahman said.

More hostages taken

In another part of the capital, armed men in olive green uniforms stormed the office of an Italian aid group and seized two Italian women and two Iraqis. It was only the second known kidnapping of foreign women since a wave of hostage-takings began this year.