By TIM WEINER and LYDIA POLGREEN
 
ORT-AU-PRINCE, Haiti, March 7 — At least five people were killed Sunday when gunfire broke out near the presidential palace, after thousands of Haitians, including rebel leaders, marched peacefully through the capital to the palace gates.

The demonstrators, who had marched beside a convoy of armed United States marines and French troops, were calling for a new government and a new army.

Four Haitians and a Spanish television journalist died from gunshot wounds, said Dr. Ronald Georges, a surgeon at the overwhelmed emergency room of the Canape Vert Hospital in the capital. At least 20 people were wounded by "high-velocity weapons," Dr. Georges said.

The carnage marred a march that was by far the largest in Haiti since President Jean-Bertrand Aristide fled into exile a week ago under American pressure, after a monthlong rebellion that had threatened to plunge Haiti into anarchy.

An international peacekeeping force led by the United States has since begun to take control in Haiti, but both Aristide supporters and opponents remain heavily armed, resisting American calls to turn in their weapons. The results of their recalcitrance were plainly displayed Sunday, when men identified by witnesses as militant supporters of Mr. Aristide fired on a crowd of peaceful demonstrators.

Thousands of Mr. Aristide's opponents were gathered near the palace gates when the shooting started. Witnesses said the gunmen were chimères, the toughs Mr. Aristide had used to enforce his authority.

"The chimères just started shooting at us out of nowhere," said Sacha Baker, an opposition protester. "The cops started shooting back, and a lot of people were hit. The marines were nowhere to be seen."

Three marines returned fire from inside the palace gates, said Maj. Richard Crusan, a Marines spokesman in Port-au-Prince. He said a first volley came from outside the gates at 2:40 p.m. and a second from outside the gates eight minutes later.

A small contingent of marines came from inside the palace gates to aid some of the wounded. The marines who were with the parade of demonstrators all morning did not go all the way to the palace, but stopped to secure checkpoints a few blocks away at midday, about two hours before the shooting.

Three witnesses said the gunfire had begun in the Rue Lamarre, 100 yards from the palace gates. They said the shooting stopped after a group of marines came from inside the palace gates toward the armed Aristide supporters, then resumed after the marines went back to the palace carrying wounded people.

"The Marines need to change the rules of engagement," said Charles Baker, a prominent Aristide opponent who helped bring the wounded to the hospital. "They need to protect us or they need to go home and let us protect ourselves."

At the hospital emergency room, doctors struggled to cope with the nearly two dozen gunshot victims. The most seriously wounded lay on gurneys; half a dozen men writhed in pools of blood on the floor. Orderlies in lime-green suits struggled to mop up the pools of blood as each victim passed through, but their yellow buckets were soon full of crimson water.

"We have just two operating rooms," Dr. Georges said. "We are doing the best we can."

In the waiting room, a woman in a black cap screamed: "César is dead! César is dead! We were just together marching, and now he is dead!" Inside the emergency room, behind a screen, lay a dead man, his head covered with a white sheet. A piece of paper taped to his belly identified him: César Milfort.

Guy Philippe, the rebel leader whose actions helped push Mr. Aristide into exile, visited victims at the hospital, his face contorted as he saw their wounds. Mr. Philippe, who has said he would disarm his men with the expectation that American troops would protect the Haitian people but has not yet done so, criticized the marines. "They haven't done anything," he said.

Ricardo Ortega, the New York correspondent for the Spanish broadcast network Antena 3, died of a gunshot wound to the abdomen. The wounded included an American photographer, Michael Laughlin, 37, who was on assignment for the South Florida Sun-Sentinel, of Fort Lauderdale. He was shot in the shoulder and cheek, but the wounds were not life threatening, doctors said.

The march to the presidential palace began at about 9:15 a.m., less than six hours before the shooting, when about 50 marines, French soldiers and Haitian policemen rolled up to St. Peter's Church in Pétionville, a suburb of Port-au-Prince, during a Mass.

Several hundred demonstrators immediately set out with the rolling convoy of foreign soldiers, making them part of the march. The river of people grew to many thousands as it reached Toussaint L'Ouverture Boulevard, named after the leader of the slave revolt that created a free Haiti in 1804.

The demonstration surged past the Marine convoy, carrying troops armed with .50-caliber machine guns and assault rifles. Mr. Philippe, the rebel leader, appeared in the crowd next to the marines. The demonstrators sang his praises, and a marine telephoned superiors to report Mr. Philippe's presence.

Mr. Philippe has called for the restoration of the notorious Haitian Army, and so did some demonstrators. The army overthrew Mr. Aristide in 1991 and the United States restored him to power in 1994.

The marchers supported a new government, freed both from the influence of Mr. Aristide's party, Lavalas, and from United States forces.

"We don't want Lavalas!" the crowd sang. "We don't want occupation!" Others chanted "Bring back the army!" and "Fix the police!" They also cheered for Louis-Jodel Chamblain, a former Haitian military officer convicted of killing Aristide supporters.

Hundreds of the marchers called for the arrest of Mr. Aristide's prime minister, Yvon Neptune. Pamphlets, signs and chants supported a retired Haitian Army lieutenant general, Hérard Abraham, to replace him. A seven-member "council of elders" is supposed to select a new prime minister in two or three days.

Mr. Abraham was a member of a military junta in the late 1980's. But, unique among modern Haitian Army officers, he handed power to a civilian leader, the sitting chief justice of the Supreme Court, in 1990. That opened the way to Haiti's first free elections in December 1990, which Mr. Aristide won, only to be overthrown by the army the next year.

As radio reports filtered through the crowd about a possible counterdemonstration by Aristide supporters, the anti-Aristide crowd sang a song in Creole about them. It went something like this, "They're here, they're weird, look out for them."