SANTO DOMINGO, DOMINICAN REPUBLIC, SEPT. 18 -- Lt. Gen. Prosper Avril, a career officer close to Haiti's rulers since the Duvalier dictatorships, declared himself president early today after a palace coup that ousted Lt. Gen. Henri Namphy.

Avril, in a televised speech at 2 a.m., said he agreed to take over the government at the petition of noncommissioned Army officers who were "sickened" by Namphy's rule. Yesterday's coup came at the end of one of the bloodiest weeks in the 31 months that Namphy controlled Haiti, a period of repeated political killings.

The new Haitian leader, who was armed forces adjutant general and an aide to Namphy, pledged that Haiti would respect human rights and that an internal "dialogue will be honored for the sake of national reconciliation."

Haiti's Radio Metropole reported that four Haitians were killed today in the capital, two beaten and burned to death in apparent vengeance by a mob near St. Jean Bosco Catholic Church, which was burned in an attack by thugs last Sunday. At least 11 persons were killed in that attack.

Today's victims near the church were believed by the crowd to have participated in the earlier attack, the radio said. One woman passerby was killed by random police gunfire, and the fourth person killed was said to be a supporter of Port-au-Prince mayor Franck Romain, who reportedly had sought asylum in the Dominican Republic before the coup. He has been accused of playing a role in recent violence.

Avril, in a meeting this afternoon with the diplomatic corps, including U.S. Ambassador Brunson McKinley, said he would like to see a return to civilian rule in Haiti, but he mentioned no timetable, diplomats said.

The U.S. Embassy in Port-au-Prince responded with cautious optimism to Avril's statements.

"We consider his themes to be very hopeful. But we are waiting to see what kind of actions this government takes to put them into effect," embassy spokeswoman Susan Clyde said in a telephone interview.

Because Avril served throughout the 1970s as aide-de-camp to dictator Jean-Claude Duvalier, toppled Feb. 7, 1986, many Haitians remained wary of his intentions, according to diplomats, Haitian journalists and observers reached in the Haitian capital.

Traffic was described as thin but moving normally by midday in the tangled streets, which were patrolled by military vehicles. Gunfire that reverberated in the city throughout the night died down by late morning. The international airport remained closed.

Haitian radio and television stations carried terse reports about the coup, butlimited themselves to rebroadcasting Avril's speech and following the Seoul Olympics.

Namphy arrived with his wife and one daughter at about 8:30 this morning here in the capital of the Dominican Republic, which shares the island of Hispaniola with Haiti. He checked into a luxury hotel under the protection of Dominican security. Foreign Ministry officials said he had been granted temporary asylum on "humanitarian" grounds.

Through the hotel manager, Namphy said he would not make any public statement because he is "a military man, not a politician."

Romain, a politician closely associated with the paramilitary squads of the Duvalier rule called Ton-Tons Macoutes, was reported to be in the Dominican Embassy in Port-au-Prince awaiting a flight to Santo Domingo. He gained the mayor's post in tainted, Army-run elections in January.

Officially, the expulsion of Namphy was the only change made so far by Avril. Confusion surrounded the position of Col. Jean-Claude Paul, the commander of the key Dessalines Barracks in the Haitian capital, who was indicted in March by a Miami grand jury on charges of cocaine trafficking.

The government spokesman, Frantz Lubin, told The Associated Press late yesterday that Paul had been promoted to commander-in-chief of the armed forces. But diplomats said today that Avril told them Paul had not been promoted and did not participate in the coup.

Diplomats said the coup was carried out by hundreds of noncommissioned officers from the Presidential Guard, an elite corps that defends the National Palace. Paul's Dessalines Barracks, which garrisons 700 troops and stands just behind the palace, was said not to be involved.

Sgt. Joseph Heubreux of the Presidential Guard appeared on television to introduce Avril as "the most honest officer" in the 7,000-member Haitian armed forces. Heubreux said Namphy had been ousted because he "had not satisfied the wishes of the Haitian people."

The week's violence began with the assault by machete- and rifle-wielding attackers last Sunday on the St. Jean Bosco Church as a radical antigovernment priest was delivering a sermon. The church was burned, 11 in the congregation killed and more than 70 wounded.

The following day another church was burned. Last Monday night, six persons who were not named but whose faces were visible appeared on government television to declare that they had participated in the attacks and would continue them. Mayor Romain told reporters that the priest, the Rev. Bertrand Aristide who was not hurt in the attack, had been "duly punished."

On Wednesday, the same assailants raided the maternity ward of the Port-au-Prince General Hospital, ripping sheets off patients' beds looking for a young pregnant woman recovering from a stab wound in the first church attack. They said they wanted to kill her, but did not find her.

The attacks, carried out by Haitians described as being tied to the officially disbanded Ton-Tons Macoutes, caused "extreme discontent" in the armed forces, said government spokesman Bernard DeGraff today by telephone. The officers wanted to put an end to the image that the Ton-Tons Macoutes were protected by the government, he said.

Sporadic shooting in the capital overnight was believed to be between Army soldiers and Ton-Tons Macoutes gunmen. Romain's home was sacked this morning.

Namphy was part of a governing council that ruled from Duvalier's departure until Feb. 7, 1988. Elections in which one of several independent candidates seemed likely to win were stopped amid a Ton-Tons Macoutes rampage last Nov. 29 in which at least 34 people were killed.

Namphy organized another election in January, which Leslie Manigat won amid accusations of fraud. But Namphy ousted Manigat June 19 when Manigat moved to consolidate his power over the military. Avril, who has been a key behind-the-scenes adviser to every government since 1971, helped organize that coup.

Reuter added from Washington:

U.S. diplomats said Avril's ascendancy offered an opportunity to meet some of the conditions that the United States has set for a resumption of U.S. aid to Haiti.

"I think we feel this is someone who can be worked with," said one American official who asked to remain unidentified. "It's a change for the better, probably. What he has said so far is pretty hopeful.

"Obviously he has some restraints on himself from other sections of the military. It's not clear what exactly he can do. But I would agree it's a hopeful sign and probably a step for the better."

Larry Birns of the nongovernment Council on Hemispheric Affairs said, "The problem with what to do about Col. Paul will eventually be a major but delicate issue for Avril to confront. Ultimately he must oust Paul and hand him over to the U.S."

Birns said he was "cautiously optimistic" that Avril's rule would improve order.