By TIM WEINER and LYDIA POLGREEN
 
PORT-AU-PRINCE, Haiti, March 1 — Armed rebel leaders swept into this capital this morning and occupied the national police headquarters, eyeing the presidential palace next door, as a handful of United States marines looked on.

A wave of thousands of dancing, cheering people rounded the boulevard between the police headquarters and the palace minutes later, shouting "Victory!"

There was no resistance, simply the organized chaos of a coup.

But blood did flow in the streets of the capital today. At least four men identified as supporters of the deposed president, Jean-Bertrand Aristide, were found shot to death in one neighborhood today. And armed rebels said in interviews that they intended to kill suspected gang members loyal to the president.

A total of 150 marines, who landed in Haiti on Sunday night, took up positions at the international airport and the Coast Guard port here as well as the presidential palace. They were the leading edge of an international force due to grow in coming days.

[In Washington on Monday, Defense Secretary Donald H. Rumsfeld dismissed as ridiculous any notion that Mr. Aristide had been abducted by the United States military and taken out of the country. "To the extent that the United States was involved, it was through the Department of State," he said at a news conference.]

The United Nations Security Council, meeting in emergency session on Sunday night, passed a resolution approving a multinational force for Haiti. Fifty troops from France arrived today.

Secretary of State Colin L. Powell said today that the force would help install a "responsive, functioning, noncorrupt" government.

"We have ways of talking to the various rebel leaders and I am pleased that at least so far they said they are not interested in violence any more and they want to put down their arms," Mr. Powell told CNN.

They did not put down their guns today.

In interviews, the rebel leaders, Louis-Jodel Chamblain, a former death-squad leader, and Guy Philippe, a former police chief, thanked the United States for moving to secure Haiti after the fall of President Aristide on Sunday morning.

"We're grateful to the United States!" Mr. Chamblain shouted through the window of his truck en route to the presidential palace.

Mr. Philippe said: "The United States soldiers are like us. We're brothers. We're grateful for their service to our nation and against the terrorists of Aristide."

These men — whom Mr. Powell characterized last week as thugs — and a few hundred of their followers are now the domestic face of national security in Haiti. Several truckloads of the national police, the ineffectual force formed by Mr. Aristide after he dissolved the notorious Haitian Army in 1995, joined Mr. Chamblain's rebel caravan today after exchanging hugs and handshakes with rebel fighters.

Mr. Philippe vowed that the Haitian Army would rise again. The army overthrew Mr. Aristide in 1991 and ran a violent junta until the United States military reinstated the president in 1994.

"We are going to remobilize the army, constitutionally," he said in an interview. "We are going to make a new Haiti."

Mr. Chamblain drove down to the capital from the town of St. Marc this morning in a caravan of about a dozen vehicles and stopped at two police headquarters, where he was embraced by the captains and rank and file. Mr. Philippe drove down from Gonaïves, where the uprising against Mr. Aristide began Feb. 5.

Mr. Chamblain's caravan included men wearing camouflage gear, including one with a surplus United States Marine jacket, bearing assault weapons and carbines. As it entered the heart of Port-au-Prince, heading up Martin Luther King Boulevard, other trucks and vans joined it, including one with a sign reading, "Liberation Front — Armed Forces of Haiti."

It grew like a river fed by rivulets in a heavy rain, ending in a small ocean of humanity at the presidential palace.

Mr. Aristide's home in the suburb of Tavarre was sacked, meanwhile. Books, pictures and a grand piano lay among the rubble.

Mr. Aristide, the slum priest who became his country's first elected president, fled Haiti at dawn on Sunday under intense pressure from the United States and the verbal threat of an invasion of the capital by the armed insurgents. His exile began today in the Central African Republic.

Joy at his departure was hardly universal. Jackson Thomas, 32, who lives in La Saline, a tough slum where Mr. Aristide's strongest support lay, said: "It's a violation of our Constitution. This president was elected for five years. It feels like we don't have any friends in the international community."

The chief justice of the Supreme Court, Boniface Alexandre, was sworn in as the leader of a transitional government until elections in 2005, and Mr. Philippe said he pledged loyalty to him.

But there is little semblance of a government in Haiti today. The so-called unarmed rebels — a broad but very loosely-knit array including wealthy and politically sophisticated people, including former Aristide supporters — remains a coalition that has not quite coalesced.

Charles Baker, a well-to-do businessman, and one United States official said the unarmed opposition, under the guidance of the United States, was trying to form an unofficial ruling coalition, an unelected council of elders to run Haiti.

Political opposition leaders said they were taken by surprise by the rapidity of Mr. Aristide's departure, and they are still scrambling to create a coherent response.

Philippe Oriol, a member of the Group of 184, a coalition of groups that marched in the streets to demand Mr. Aristide's resignation, said that maintaining order must be the first priority.

"The first step is to secure the town," he said. "Then we have to rebuild the country."

Violent clashes between government supporters and armed militants have left as many as 100 people dead since early February, and there has been widespread looting of ports, shops and houses in several cities. But a relative calm, reinforced by the presence of the marines, seemed to hold this morning.

Mr. Aristide's departure had been long sought by his political opponents, who rejected a power-sharing plan pushed by the United States. It was a surprising exit for a man who once seemed poised to deliver his long-suffering nation "peace in the mind, peace in the belly," as his campaign slogan had promised.

He was felled by American pressure and the threat of an attack by the armed insurgents, who may number no more than 500 men in arms, but threatened to depose him by force unless the president left power.

Mr. Aristide, once a radical Roman Catholic priest, was elected president overwhelmingly in 1990, overthrown in 1991 and returned to power in 1994 by an American-led military invasion.

He won a second five-year term in office in 2000, but his power eroded as government corruption and anger in the streets grew out of control. After the armed rebellion erupted in Haiti's north on Feb. 5, the rebels quickly seized half the nation and threatened to storm the capital.

Hundreds of people have tried to flee in boats bound for Florida, but most have been intercepted by the United States Coast Guard and shipped back.

American policy toward Mr. Aristide shifted swiftly. In July, Brian Dean Curran, then the United States ambassador here, said, "The United States accepts President Aristide as the constitutional president of Haiti for his term of office ending in 2006."

But the Bush administration decided in the past three days, as a senior administration official said on Saturday, that "Aristide must go."

Troops from other countries — Canadian officials promised on Sunday that they would provide military assistance as part of an international force — will now try to stabilize the country, but the task could take years.