Under cover of the early-morning darkness, President Jean-Claude Duvalier today left Haiti, handing over power to a joint military-civilian council and ending two generations of a repressive family dictatorship.

Duvalier flew in an American military transport plane to France, where he was to stay for several days before moving on to another country that will agree to accept him.

Duvalier's dramatic downfall, and the announcement of a government dominated by the military, sent hundreds of thousands of Haitians pouring into the streets this morning, blaring car horns, destroying the Duvalier portraits and monuments that line this capital's boulevards, and wreaking bloody revenge on members of the president's notorious security force popularly known as the Ton-Tons Macoutes.

Reporters saw almost a dozen bodies of alleged Ton-tons Macoutes members in the streets. Residents, saying they were overjoyed at the end of Duvalier's rule, directed reporters to streets where there were even more bodies.

Unconfirmed reports said 20 persons had been killed and 75 wounded in the violence. A mob reportedly went to the cemetery where the founding member of the Duvalier dynasty, Francois (Papa Doc) Duvalier, was buried and exhumed the coffin, trampling and scattering the remains. This report also could not be confirmed.

In the Delmas suburb, another mob reportedly attacked the car dealership and other businesses owned by Duvalier's father-in-law, Ernest Bennett, stealing hundreds of automobiles and carrying off furniture and window frames as troops looked on.

Cheering crowds gathered on the sidewalk in front of Duvalier's palace, which had been closed to the public for years.

Sporadic bursts of automatic weapons fire were heard throughout the day, and many shops were reportedly looted and burned.

A curfew was declared at 2 p.m., and the U.S. Embassy advised 6,000 American citizens believed to be here to stay indoors until further notice.

Duvalier, along with 21 members of his family and three bodyguards, flew out of the international airport at 3:46 a.m. aboard a U.S. Air Force C141, which was provided under an agreement reached by Duvalier and the ambassadors from France and the United States. The U.S. Embassy, which apparently took an increasingly strong hand in persuading Duvalier to leave in the face of the protests here, announced his departure in an unusual 4 a.m. press conference on the lawn of the embassy compound with reporters pressed against the metal fence outside.

"He determined that he could no longer continue in power without resorting to increased repression and government-inspired violence, and he was unwilling to do that," said U.S. Embassy spokesman Jeffrey Lite.

[In Kingston, Jamaican Prime Minister Edward Seaga's government said it joined with the United States in three days of secret talks with Duvalier in Port-au-Prince to persuade him to step down, The Associated Press reported.]

Haitians found out about the change of power in a taped radio broadcast about three hours later, in which Duvalier cited the violence here and declared, "I take God as a witness that I have never wanted bloodshed."

"Unfortunately, during the recent past, we have had to deplore that there have been a certain number of victims," Duvalier said.

"Today, I have not been able to detect through a meticulous consideration of the situation any sign which would encourage me that this nightmare of blood would be spared to my people," he continued. "That is why, wanting to go down in history with my head held high with a clean conscience, I have decided tonight to trust the destiny of the nation and the power to the armed forces of Haiti, desiring that this decision will allow a peaceful and rapid solution to the present crisis."

Duvalier's taped announcement was followed by the playing of the national anthem and then a communique from the new five-member national governing council and its president, Army Chief of Staff Lt. Gen. Henri Namphy, who said they had no "political ambitions, while promising to respect human rights and move toward democratic elections."

"In all the provinces there are popular demonstrations, during which the lack of self-control of some or the misunderstanding of others has very often harmed innocent victims and finally created a state of agitation, which caused the frightful specter of civil war to loom," Namphy said.

The statement gave no indication as to whether the council intended to maintain power or hand it over to an elected government. Later, Namphy and the other four junta members -- including human rights advocate Gerard Gourgue -- greeted foreign ambassadors in the ornate Yellow Room of the stately white presidential palace where Duvalier had lived since he was a little boy, when his father, Francois Duvalier, was first elected president in 1957.

After the hourlong reception, when asked by reporters when elections might take place, Namphy said that a declaration would be coming soon. Gourgue added, "We will have to reflect on that."

The other members of the new governing council are: Col. William Regala, Col. Max Valles and Public Works Minister Alix Cineas. Col. Prosper Avril was named an adviser to the council.

The transition of power from Duvalier to the military-civilian council apparently was made final yesterday afternoon when Duvalier decided that his situation here had become untenable and that it was time for him to leave.

Duvalier first met with the French ambassador at about 2 p.m. in the palace and requested political asylum, according to well-informed sources. After the ambassador agreed to a temporary haven, within the hour Duvalier also met with U.S. Ambassador Clayton B. McManaway, and requested an airplane to take him into exile.

U.S. officials arranged for a C141 transport plane to be sent here from Fort Bragg, N.C., and to arrive in Haiti at 2 a.m.

Amid the diplomatic flurry and the heightened speculation that Duvalier's departure was imminent, journalists converged on the airport shortly before midnight, when the first cars and jeeps filled with luggage started arriving. The transport plane landed at exactly 2 a.m., but Duvalier was nowhere to be seen, leading some nervous U.S. diplomats to suspect that he might have changed his mind. All communication links with the outside world were temporarily cut during the delicate transition.

Duvalier finally arrived at 3:26 a.m., in a motorcade of nine luxury cars followed by a green military flatbed truck filled with uniformed troops carrying rifles.

In the lead car were Gen. Namphy and Cineas.

Duvalier was in the third car, a silver-gray BMW, which he drove himself. He looked determined as he plowed the car through a throng of television cameras, blaring the horn. Next to Duvalier in the front seat was his wife, Michelle, whose growing economic and political power in the government had become a source of controversy here. She appeared tense as she held a cigarette and stared at the reporters pressed against the car.

Most of the other cars were filled with military officers in their beige khaki uniforms, except for the eighth, which was filled with blue-uniformed Ton-Tons Macoutes.

Informed sources said later that Duvalier was late because he gave a farewell party at the palace.

During the 1 3/4-hour delay on the runway, the giant troop transport plane reportedly used so much fuel that it later was forced to make an unscheduled refueling stop in Puerto Rico before the flight to Europe.

The U.S. Embassy later confirmed that the 24 persons who left with Duvalier were 21 family members, including his two children, his wife's two children from a previous marriage, some of his wife's sisters and his mother.

Four U.S. Embassy officials were at the airport. The Reagan administration had been applying subtle but increasing pressure on Duvalier to leave since November, when protests throughout Haiti left at least four persons killed by Army troops sent in to quell the disturbances.

Officials here denied that the U.S. government "pulled the strings" on Duvalier to get him to leave, but clearly signaled that they welcomed his departure.

"His [departure] was a useful step," said embassy spokesman Lite, "and we're looking forward to a transition to a new government. The decision was his decision."

Asked if the United States encouraged Duvalier to leave, Lite said, "He was not discouraged by us." The change of government, however, did not mean an automatic resumption of U.S. aid to Haiti, which was suspended last week because of human rights violations by the Duvalier government.