U.S. troops broke Saddam Hussein's 24-year grip on the Iraqi capital Wednesday as cheering, dancing crowds shouted, "Oh, Iraq!" and, with help from the Marines, toppled a four-story statue of the president, dragging its head in the streets while children pelted it with garbage.

"Victory! We are free!" the crowds called out. "Thank you, President Bush!"

Three weeks after the United States went to war against Hussein's regime, the U.S. Army and Marines took control of central Baghdad and dealt a definitive blow to the Iraqi leader's aura of invincibility, unleashing wild celebrations as well as looting and fires.

"The game is over," Mohammed Douri, Iraq's ambassador to the United Nations, conceded in New York.

U.S. officials echoed the sentiment. "We are seeing the collapse of the central regime authority," said Vice President Dick Cheney in a speech in New Orleans. At the Pentagon, Defense Secretary Donald H. Rumsfeld, who compared the toppling of Hussein's statue to the fall of the Berlin Wall, declared, "This is a very good day."

For all the celebrating, however, the war in Iraq is hardly over. U.S. and British forces, Rumsfeld said, still must gain total control of Baghdad and other Iraqi cities, especially Tikrit, north of the capital, Hussein's hometown and a stronghold of his supporters.

Military sources at the U.S. Central Command in Doha, Qatar, said they were assessing the strength of Hussein's military, paramilitary and civilian loyalists in and around Tikrit. One source said U.S. forces would cut off Tikrit from Baghdad and assault the city with airstrikes.

Rumsfeld said the allies also need to account for, capture or otherwise deal with Hussein, his sons and other senior Iraqi leaders; capture Mosul and Kirkuk in the north to secure surrounding oil fields; and capture or kill Iraqi fighters scattered throughout the country.

A senior Pentagon official, speaking on condition of anonymity, said a peacekeeping force of more than 200,000 troops probably will be needed in Iraq to help maintain order, distribute relief supplies, restore civil services and secure suspected chemical weapons sites.

After a day of looting in Baghdad in which residents stole everything they could carry from government ministries, the city spent an uneasy night filled with scattered fighting. In an area near downtown, Marines opened fire on a taxi that didn't stop when ordered and killed three men inside.

No weapons were found.

The Marines pounded a pocket of soldiers and paramilitary fighters for long, intense periods throughout the night on the east side of the Tigris River, above the northernmost of five bridges connecting western Baghdad with the Old City.

Residents waving white flags tried to run across the bridges to flee the fighting, but units of the Army's 3rd Infantry Division, which held four of the five bridges, pushed them back. Some of the gunfire struck small boats that also were trying to cross the river.

"We think they're trying to buy Saddam some time to make a final stand," said Col. John Toolan, commander of the 1st Marine Regiment. The Marines held the upper hand, he said, but took nine casualties, including one death.

At daybreak today, many residents resumed looting, said Col. Geff Cooper, a Marine reservist from San Bernardino.

On Wednesday, the day had begun with sporadic fire against the Marines during the morning and early afternoon, from small pockets of poorly organized paramilitary groups. One firefight broke out near a 75-acre government complex close to the center of Baghdad. Snipers opened fire from the rooftops. Marines responded with shoulder-fired rockets and a hail of small-arms fire.

. The Marines took over the area for a command post. It was not immediately known whether there were any casualties. In the complex, the Marines found a police station, a jail, military barracks, a hospital and a headquarters of the Iraqi secret police. Cells in the jail were not much bigger than high-school lockers. There was evidence that prisoners had been fed through slots in the doors.

The 'Tipping Point'

Shortly before 5 p.m., the city reached what Army Brig. Gen. Vincent Brooks, a U.S. Central Command spokesman, called the "tipping point," when residents realized that "the regime is in disarray and much of Iraq is free from years of repression."