Battling small-scale resistance, U.S. Army units seized some of the last remaining strongholds of President Saddam Hussein's government today, including the headquarters of the Special Republican Guard, which was commanded by Hussein's son and vaunted as his most loyal and best-trained defense force.

The Army sweep through western Baghdad's main neighborhood of ministries and government palaces was matched by equally broad advances by Marine columns moving through residential and commercial quarters on the eastern side of the Tigris River. The coordinated occupations left U.S. military forces controlling the heart of the Iraqi capital, a sprawling city of 5 million people, except for scattered resistance by die-hard fighters in houses, office buildings and other redoubts.

Maj. Gen. Buford C. Blount III, commander of the Army's 3rd Infantry Division, told reporters that Baghdad's fall means the fighting that began with a U.S.-British invasion from Kuwait three weeks ago is nearing its end. "Not every area in Baghdad is secure," he said, "but the central part of the city, the heart of the city, is secure. . . . The end of the combat phase is days away."

As they took control of government buildings and blew up tons of munitions, 3rd Infantry Division troops encountered a warm welcome from cheering Baghdad residents. Soldiers who dismounted from their M2 Bradley Fighting Vehicles to clear houses of remaining Hussein loyalists were offered information, food and drink by residents who expressed joy at seeing the end of more than three decades of Baath Party rule.

"Today's been a big day," said Capt. Felix Almaguer, 29, of Summit, N.J., a battalion intelligence officer in the 3rd Infantry Division. "They've been coming out of the woodwork to help us out."

The assistance from the population made it easier to target government strongholds, military officials said. "We've pretty much blown up every headquarters," Almaguer said. "There's probably not a pro-regime government building that hasn't been hit yet."

The U.S. vehicles were cheered by crowds as they made their way north along the same route where they were met by bullets and rocket-propelled grenades two days ago. Civilians asked to have their pictures taken with the Americans, soldiers said.

Throughout the day, Iraqis came forward to try to help the Americans, pointing out arms caches and safe houses of Hussein loyalists. Teams of U.S. troops rigged the arms depots with explosives and blew them up, triggering thunderous booms and sending up billowing smoke at intervals into the evening.

The generally joyous reaction to the government's collapse was received with satisfaction by soldiers who had seen little evidence until today that Baghdad residents were pleased to see them.

"It's good to hear," said Capt. Fred Cannan, 33, a military planner for the 3rd Battalion, 15th Regiment. "That's why we're here."

"It makes you feel kind of good, like you actually did something," said Sgt. 1st Class Vincent Phillips, 37, of Washington, Pa.

But intermingled with the cheers and explosions of munitions were the booms of mortar rounds and artillery as U.S. gunners targeted firing positions of Hussein's remaining die-hards. The 3rd Battalion, 15th Regiment, which held several positions in central Baghdad on the western side of the river, killed 15 to 20 fighters, mostly rocket-propelled grenade teams in groups of two or three, said Maj. Denton Knapp, 38, of Gillette, Wyo., the battalion's executive officer.

After an Iraqi counterattack against U.S. positions failed early Tuesday, "the fighting died down significantly," Almaguer said. "It's been very light and sporadic contact."

Said Knapp, "It seems like they're realizing they're encircled."

In one incident reported to 3rd Battalion officers by radio, a Bradley fired a high-explosive 25mm round into a mosque in the Ilam neighborhood after receiving rocket-propelled grenade fire from it. The platoon commander said local Iraqis told him combatants from Syria and Lebanon were inside the mosque and had been there for several days.

"These third-country nationals are coming out and fighting for Saddam, and it's pretty apparent that the locals are not appreciative," Almaguer said. He said 28 of the 30 prisoners taken at a highway junction in southern Baghdad on Monday turned out to be Syrians.

An interpreter who interviewed them said they had come to wage holy war against the United States in defense of Iraq. They carried thick wads of Iraqi dinars, he said.

A tank unit that seized the Special Republican Guard headquarters, the 1st Battalion, 64th Armored Regiment, also consolidated its control over a vast amusement park and parade ground near Iraq's Tomb of the Unknown Soldier, an area that U.S. military officials said had been turned into an arms depot. Large caches of weapons, including grenade launchers and rockets, were found and destroyed.

The Special Republican Guard, estimated to number 10,000 men, was said to be specially trained in urban warfare and assigned to protect Hussein and his Baath Party government. It was considered to be particularly loyal to the Iraqi leader -- and his last line of defense -- and was put under the command of Hussein's younger son, Qusay, who also commanded the National Security Council and its half-dozen intelligence and special security organizations. In the end, however, it mounted little defense in Baghdad and its headquarters offered no resistance.

Another tank unit, the 4th Battalion, expanded its hold on bridgeheads over the Tigris to link up with Marines on the eastern side of the river.

It was also a day to clear the streets of the decomposing bodies of Hussein loyalists killed by the advancing U.S. column or shot while running roadblocks.

Among them was the bloated corpse of a man in a U.S.-style desert camouflage uniform who lay on the sidewalk opposite the Sijood Palace in front of a blue Chevrolet he had been driving. The car was pushed up onto the severed trunk of a palm tree. In the car's trunk, next to a bottle of Al Capone cologne, was another clean U.S. camouflage uniform.

"The last time we were here, that's what we wore," a U.S. officer said, pointing out the camouflage pattern that soldiers dubbed "chocolate chip" a style not worn by U.S. soldiers in this war.

U.S. forces previously had refused to clear away the bodies of Iraqi soldiers and civilians who were killed in the fighting, preferring to let the Iraqi Red Crescent handle the task. But with the bodies becoming a health hazard and the government collapsing, commanders changed course and sent orders to remove and bury the corpses.

Soldiers from the Army's 3rd Infantry Division carry a torn picture of President Saddam Hussein as they ride on top of a vehicle making its way through the streets of the Iraqi capital.Members of Charlie Company from the 3rd Battalion, 15th Regiment prepare to clear a government building of any soldiers who might be inside.An Army medic tries to help an Iraqi civilian hit in the head by shrapnel in an aerial bombing.