U.S. forces tightened their control over Baghdad today, as military officials offered upbeat assessments of the progress of the war to topple the government of President Saddam Hussein.

"We are barely past the two weeks of this war, and already we've made enormous progress," Deputy Defense Secretary Paul Wolfowitz said on Fox News Sunday. "And our troops are outside of Baghdad, control Baghdad International Airport. The feared Republican Guard have suffered enormous losses, and it's clear where the end is."

Wolfowitz, who made the rounds on the Sunday morning television news shows, said Hussein's government may still control parts of Baghdad, but that it was "on its way out, no doubt about it. The end of this regime is here."

U.S. forces solidified their control of most of the international airport on the southwestern edge of Baghdad, including a VIP terminal that contains what U.S. soldiers suspect was a hideaway for Hussein. The airport is secure and is being used by U.S. helicopters, said Col. Will Grimsley, commander of the 1st Brigade of the U.S. Army's 3rd Infantry Division.

A C-130 Hercules transport plane also landed at the airport today, officers announced, a first for U.S. forces there that opened the way to greater air operations in and around the Iraqi capital.

In northern Iraq, allied forces suffered a setback when two U.S. jets bombed a convoy of Kurdish and U.S. troops as it passed through broken Iraqi lines on a key ridge near the village of Dibagah. At least 18 Kurds were killed and three American Special Operations soldiers were wounded, Kurdish officials said. A BBC television correspondent was also injured.

In Iraq's south, British troops took control of Basra, ending a two-week siege of Iraq's second largest city after the capital.

Marine Gen. Peter Pace, vice chairman of the Join Chiefs of Staff, said U.S. forces had formed a loose circle around Baghdad, taking control of most roads to and from the city and seeking to isolate it and block movement of Iraqi troops. "Baghdad, as you know, is about 15 miles or more east to west and about 15 miles north to south, so to say that you have an impenetrable cordon around the city would be a misstatement," Pace said on ABC's "This Week." "It is certainly true that we have huge amounts of combat power around the city right now, and that we have over a thousand planes in the air every day. So if it moves on the ground and it takes aggressive action, it's going to get killed."

Massive explosions rocked central Baghdad early in the day as Iraqi troops, members of Hussein's Fedayeen militia and teenage soldiers patrolled streets to protect the capital from U.S.-led forces.

A Marine battalion overran a Republican Guard headquarters and seized one of Saddam's palaces south of the city, according to the Associated Press.

U.S. officials described the fighting in and around Baghdad as very one-sided. "In some cases we take a few wounded, and in some cases we have one or two killed," U.S. Brig. Gen. Vincent K. Brooks told reporters at Central Command headquarters in Doha, Qatar, this morning. "But in all cases, we inflict a considerable amount of destruction on whatever force comes into contact with us. It just is not worth trying to characterize by numbers."

Iraqi officials remained defiant. "This regime will not be defeated by mercenaries, God forbid," Information Minister Mohammed Saeed Sahhaf told reporters at his daily briefing in Baghdad today.

Iraqi forces showed off a destroyed U.S. tank to reporters on a highway leading south out of Baghdad and said four U.S. soldiers had been killed, according to news wire reports. Iraqi state television also showed brief footage of a smiling Saddam in military uniform presiding at a meeting it said was held Sunday with his top aides, the news service said. Separately, TV quoted Saddam as saying anyone who destroys a coalition tank, armored personnel carrier or artillery will receive a $5,000 reward. TV also broadcast a statement attributed to Hussein urging soldiers separated from their regular units to join up with any unit they can find.

The U.S. military opened the battle for Baghdad on Saturday by dispatching more than 40 tanks and other armored vehicles through the capital's southwestern quadrant. Sunday morning, military officials said that between 2,000 and 3,000 Iraqis had been killed in the operation and that there would be more forays toward the city's center before long.

Just west of Baghdad, five Russian Embassy employees evacuating the capital were injured when their convoy was caught in a firefight between Iraqi soldiers and U.S. troops, witnesses said.

Russian Ambassador Vladimir Titorenko and 22 other embassy staff members and journalists were traveling in eight cars past Iraqi positions just west of the city when the Iraqis came under intense fire from coalition forces, according to Alexander Minakov, a Russian reporter with the RTR television network.

"Naturally the Iraqis started to return fire. So we found ourselves caught in the crossfire, basically," Minakov told the state-controlled network. The driver of the ambassador's car was hit in the abdomen and had to undergo an emergency operation in an Iraqi hospital in Feluja, about 35 miles west of Baghdad, he said. Two other embassy employees were also seriously injured and two had slight injuries, according to the journalist.

Today's apparent bombing of the U.S.-Kurdish convoy in northern Iraq was the worst "friendly fire" incident of the war. Among the 45 Kurds wounded in the attack was Waji Barzani, brother of one of the top leaders of the Iraqi Kurds. The Kurds are fierce adversaries of Hussein's government and have put their combat forces under U.S. command.

BBC reporter John Simpson, who was traveling in the convoy, earlier reported that at least 10 people were killed. "This is a just a scene from hell here. There are vehicles on fire, bodies lying around, and there are bits of bodies around me," Simpson said.

U.S. military officials were investigating that incident.

The U.S.-Kurdish move to Dibagah had been part of a broad thrust deep into Iraqi-held land in the north. U.S. jets bombed Iraqi army positions from Ain Sifne, 15 miles north of Mosul, to Khazer, which lies about 25 miles to the city's southeast. Where the Iraqis abandoned camps and trenches, Kurdish militiamen moved in. On occasion, the Iraqis have counter-attacked. After the friendly fire incident, the Kurds and their U.S. allies abandoned Dibagah.

The allied setback in the north was offset in the south, where hundreds of British troops in Challenger II tanks and Warrior armored vehicles punched into the center of Basra, apparently ending a two-week standoff.

The British advance came from two directions and involved two battle groups for a total of 28 tanks and 28 armored vehicles, with a third battle group in reserve. By nightfall, with a heavy layer of smoke from several fires engulfing the city, the British controlled the entire southern half of Basra but were still fighting sporadic battles with Baath Party militiamen armed with assault rifles, mortars and rocket-propelled grenades. As Iraqi government authority disintegrated, widespread looting broke out.

Also in Basra, the house of Gen. Ali Hassan Majeed, Hussein's cousin and close confidant, was bombed by two allied warplanes, U.S. Central Command said. It was not clear whether the strike killed Majeed, who is known as "Chemical Ali" because he allegedly ordered the use of chemical weapons on Kurds in the country's north who had rebelled in coordination with Iran during the 1980-88 war.

Brooks said on Sunday that the body of Majeed's bodyguard was recovered from the wreckage, "but as far as Ali, who knows."

Asked whether Chemical Ali had been killed, Iraqi information minister Sahhaf told reporters in Baghdad: "Let them [bask] in their illusions."

British troops in the town of Zubair, about 10 miles southwest of Basra in southern Iraq, said Saturday that they discovered a military warehouse containing the badly decomposed remains of hundreds of people in neatly arranged wooden boxes. One room in the warehouse had meat hooks hanging from the ceiling and another was pockmarked with bullets, according to journalists who visited the site.

There was no indication when the bodies were placed there. Basra and the surrounding marshlands were major battlegrounds during the Iran-Iraq war. In addition, the area's largely Shiite population rose up against Hussein's government after the 1991 Persian Gulf War, provoking a bloody crackdown by the Iraqi army.

Brooks said the site would be investigated to determine if war crimes had been committed there.

Iran claimed that the bodies were Iranian soldiers killed during the 1980-88 Iran-Iraq war, state-run Tehran radio reported Sunday.

"We officially call on the International Committee of the Red Cross to carry out their responsibility and immediately take the bodies from the invading forces and hand them over to the Islamic Republic of Iran," the radio quoted Gen. Mirfeisal Baqerzadeh, the head of Iran's Committee for Searching for the Missing in Action, as saying.

In the town of Aziziyah, about 40 miles southeast of Baghdad, Marines searched a school for possible chemical and biological weapons after receiving a tip from an Iraqi prisoner of war. The prisoner said Iraqi military personnel had recently hidden something in a hole in the school's courtyard and then placed concrete over it.

"We don't have a clue, but we are going to dig it up and see," said Marine Maj. Gen. James N. Mattis.

The Bush administration repeatedly has charged the Iraqi government with producing and maintaining chemical weapons, citing the danger they pose as one reason for the war to destroy Hussein's government. So far, however, no chemical, biological or nuclear weapons have been found. Vials of white powder discovered Friday near the town of Latifiyah were found to contain explosives.

While military commanders had warned that Iraqi Republican Guard forces might use chemical weapons as U.S. forces closed in on Baghdad, U.S. troops advancing on the capital from the south have not encountered or found any such weapons, Brooks said.

"We haven't found anything yet," he told reporters. "We think that the places where it's most likely to be found, we haven't even gotten to most of them yet. There's a considerable number out there where there could be weapons of mass destruction or evidence of weapons of mass destruction programs. So we're not ruling anything out at this point, whether they will be there or not."

In Washington, Wolfowitz was as focused on the challenges U.S. forces will face after the war as those they faced on the battlefield today. Asked on Fox whether the Iraqis could set up a new government as quickly as the Kurds set up a territory in northern Iraq they began governing in 1991 after the first Gulf War, Wolfowitz said it would take longer.

"Six months is what happened in northern Iraq," he said. "This is a more complicated situation. It will take more than that."

Washington Post correspondents William Branigin, Alan Sipress, Rajiv Chandrasekaran, Keith B. Richburg, Daniel Williams and Sharon LaFraniere contributed to this report.