There will be more incursions, U.S. officials warned, aimed at sending a message to Baghdad's defenders that the city could be breached at any time.
More than three-dozen tanks and armored vehicles rolled through 25 miles of an industrial section of southern Baghdad on Saturday, ending their incursion at the U.S.-controlled airport.
American casualties were described as light.
Greg Kelly, a reporter for Fox News embedded with the 3rd Infantry Division, said Iraqi vehicles played a game of chicken with the Americans, speeding toward them at speeds of 80 mph or more before they were dispatched with U.S. firepower.
The U.S. forces — 26 M-1 tanks and 10 Bradley armored vehicles with the 3rd Infantry's 2nd brigade — lost one tank and an armored vehicle, but the Iraqis lost many more, National Public Radio's Ann Garrells reported from Baghdad.
In other major developments:
U.S. forces have troops stationed around three-quarters of Baghdad's perimeter: the 3rd Infantry Division along the south and southwest edges of the city; 1st Division Marines on both sides of the Tigris to the southeast; and — according to a U.S. military official speaking on condition of anonymity — at key points just to the north and northwest. That leaves only the northeast arc around Baghdad free of American forces.
Pilots said the air over Baghdad has become congested with coalition planes and they are more worried about crashing into one another than about being hit by the city's air defenses, which they can generally avoid.
The destruction caused from the air and on the ground was everywhere to see. Marine casualty and evacuation helicopters flew over crumpled bodies, charred tanks, collapsed buildings and a burning date tree forest.
The pilots of Marine Medium Helicopter Squadron 364 flew on repeated missions to Baghdad's outskirts, picking up war wounded and taking them to emergency medical centers to the south.
One helicopter carried a 5-year-old boy whose face had been blown away by shrapnel. His father, wounded in the shoulder, held the IV as the Marines loaded them both on the helicopter. On another run, six Iraqis were evacuated. When a Marine cut open the clothes of one, he exposed a military uniform underneath.
Red Cross workers reported that several hundred war wounded and dozens of dead have overwhelmed four Baghdad hospitals since Friday. A Greek doctor who just left Baghdad says there is a severe shortage of anesthesia, antibiotics and other items needed to prevent infection.
In 106-degree temperatures, amid the smoke of trenches of oil set afire by the Iraqis, Marines pressed past clusters of refugees on foot, begging for water. Bodies of Iraqi fighters were scattered along the road; at one point, Marines said they came across four seemingly lifeless men who suddenly came to life, fighting.
As other Marine units advanced north, Iraqi civilian vehicles fled south, packed with bundles and bearing improvised white flags made from torn-up towels or T-shirts.
Thirty-five miles southeast of the city, at Suwaurah, two tank companies and an infantry company of the 3rd Infantry Division rolled unopposed through the headquarters of the Republican Guard's Medina Division. They passed hundreds of bunkers and foxholes and dozens of artillery pieces, anti-aircraft gun, tanks and armored personnel carriers — all abandoned.
Hundreds of young men in civilian clothes waved as U.S. troops drove by — members of the Republican Guard who had tossed away their uniforms, the Americans believed.
An embedded Associated Press reporter says U.S. Marines near Baghdad are about out of water. But the Pentagon describes a "robust" supply line stretching 350 miles from Kuwait to Baghdad.
On Saturday, coalition aircraft struck the Basra home of Gen. Ali Hassan al-Majid, the Iraqi general known as "Chemical Ali" for ordering a poison gas attack that killed thousands of Kurds in 1988. Allied officials said the general — Saddam's cousin — was believed to be home at the time, but it was not known whether he was killed or wounded.