Elsewhere on the battlefield, at least one U.S. soldier was killed by possible friendly fire, and reporters embedded with the troops said two Marines were killed in or around Kut - one from bullet and shrapnel wounds, the other when the truck he was driving struck another on a road obscured by dust clouds kicked up by a convoy.  Three soldiers collapsed from heat exhaustion as temperatures rose about 90 degrees outdoors and over 100 degrees inside the tanks and Bradley fighting vehicles.  U.S. tanks and Bradleys destroyed more than seven Iraqi armored personnel carriers and more than 15 Iraqi tanks engaging both Republican Guard and regular army troops guarding Baghdad's southern flanks.  Scores of blown up Iraqi vehicles and dozens of dead lined the roads where the Iraqis had built fighting positions. The dead were in uniform - though it was unclear whether they were Republican Guards or regular army units.

Iraqi police officers pose in front of a mosaic of Iraqi President Saddam Hussein at Saddam International Airport near  Baghdad on Thursday.

Dozens more surrendered. The Army was slowly shuttling the prisoners to the rear as it pressed ahead toward the capital. 

In Kut, a military town on the Tigris River southeast of Baghdad, Marines from the 3rd Battalion, 4th Marines battled Iraqis building to building. The Marines jumped from rooftop to rooftop and went through all the rooms in some buildings. 

They fought at close range in a date palm grove, tossing grenades at each other. Late in the battle, a small group of Iraqis with AK-47s tried a suicide charge against a tank. 

"At the end, they came charging in a human wave - 10 to 15 guys with AKs that we mowed down," said Lt. Col. B.P. McCoy. 

He said 30 Iraqis were killed in the battle, and U.S. forces destroyed seven tanks and 20 anti-aircraft artillery. 

A Sea Knight helicopter evacuated three injured Marines, and one died in the helicopter as a doctor tried to resuscitate him. The other two had minor gunshot and shrapnel wounds. 

Another Marine was killed when the truck he was driving plowed into another on a dust-obscured road. At least 10 other Marines were injured in the accident and evacuated on a Sea Knight. 

On the outskirts of Kut, Marines opened fire on a military training academy, blowing a hole in a mosaic portrait of Saddam. 

Residents said women and children had been sent out of the city in the past days and that pro-Saddam militias had taken young men away to force them to fight the advancing coalition forces. 

"They want to give us machine guns and make us fight. We are civilians, how can we fight?" Kut resident Kasem Fasil said. "Some people, they didn't want to fight and they killed them." 

Fasil and Ali Hussein, another Kut resident, said if the Americans go to Baghdad, they are afraid Saddam's forces will unleash chemical weapons on Shiite Muslim towns like theirs. Saddam rules over a Sunni Muslim regime. 

The Marines say they found a cache of untouched chemical weapons protection suits at a bunker in the area. 

With coalition forces now well inside the so-called Red Zone radiating from Baghdad, troops had breached the region in which commanders feared Saddam's forces might resort to chemical or biological weapons. The troops were expected to don chemical protective gear despite the heat. 

So far, no such weapons have been detected. Iraq denies it still has weapons of mass destruction, and U.S. troops have yet to locate any, although they've found hundreds of chemical protective suits. 

As they advanced, Marines stopped every vehicle they met along the main road. Drivers and passengers got out of taxis and cars and stood by the road with their hands in the air. 

At a Baath Party building flying Iraqi flags, a small group of men sat clustered in a grassy area around a woman dressed in a black chador and waving a white flag of surrender. 

Many Iraqis sat down by the roadside, waving and smiling at the Marines to show they were not combatants. 

American infantry troops were moving out of the desert into farm fields with tall grass and palm trees. Small farms with rice paddies dot the banks of the Euphrates and irrigation canals. 

Iraqi soldiers had used the tall grass as cover to fire on U.S. forces, which were forced to weave through and around irrigation canals. U.S. war planes continued to roar overhead providing cover for advancing U.S. troops. 

Around the bridge that crosses the Euphrates, hundreds of tanks, Bradley fighting vehicles, armored personnel carriers and a bridge- building unit stood by in case the span had been blown up. 

One scout vehicle was hit by a rocket propelled grenade. 

"A scout just got hit by an RPG, this is serious up here," said Capt. Chris Carter from Wakinsville, Ga. 

The Marines southeast of Baghdad began the Thursday drive toward the capital protected by withering artillery and mortar fire. A massive convoy of moved along the main road leading to the Iraqi capital. 

Relentless fire from 155 mm howitzers rained on Iraqi positions near the town of Numaniyah as the Marine advance resumed. Large black plumes of smoke could be seen rising from the town and its prized Tigris River crossing, taken by American troops Wednesday. 

The Pentagon said Republican Guard reinforcements had moved out of Baghdad toward the approaching Americans. New groups of Saddam's best trained and equipped fighters were dispatched to replace units shattered Wednesday when some U.S. forces had fought to within 20 miles of the city. 

But many Iraqi units quickly abandoned defensive positions and fled, leaving behind trenches littered with everything from mortars and small arms to teapots and bedspreads. 

"When they ran, it wasn't for lack of ammo. They've got enough," one Marine said as he examined the trenches.