The head of Haiti's ruling military-civilian council fired three controversial colleagues yesterday and declared himself president of a new, streamlined governing council, as the government grappled with its most severe crisis since former dictator Jean-Claude Duvalier fled into exile last month.

Lt. Gen. Henri Namphy, who took over the country as head of the junta last month, announced the changes in a terse noontime radio address. Accounts by news services and telephone interviews with diplomatic sources in Haiti left it unclear yesterday whether the move was a power play by the military, or, as U.S. analysts suggested later, a last-ditch effort by Namphy to stem growing unrest before it toppled the new government just as street protests brought down Duvalier.

The change came as protests escalated in the capital of Port-au-Prince, with troops using new American equipment to tear-gas and club demonstrators gathered outside the gleaming white presidential palace in the center of town, news services said. At least one person was confirmed dead, shot by soldiers on the busy Dessalines Boulevard, and estimates of the number of injured ranged as high as 20, according to news services and diplomats.

The demonstrations were the most serious since the new government took power, but observers in Port-au-Prince said they were nowhere near the scale of the massive protests that shook Duvalier from power and forced him to flee into exile.

The current crisis had been building since Duvalier left the country on Feb. 7 for France, with many Haitians expressing resentment at the presence of old-line Duvalierists in the new ruling council and in several key ministries. Public pressure also had intensified on the new government to track down and prosecute former members of Duvalier's hated security force, many of whom had been leaving the country.

The crisis peaked on Wednesday when Gerard Gourgue, the only member of the original six-member junta who had been an early critic of Duvalier, resigned in a show of protest. Haitian and foreign observers said Gourgue, head of the Haitian Human Rights League who became justice minister in the new government, had grown increasingly frustrated by his inability to push his colleagues to arrest and try former Duvalier officials for human rights abuses.

Gourgue's resignation also brought to the surface an undercurrent of tension between the civilians in the new government and the military, who have been taking an increasingly powerful role in decision-making, the observers said. His public protest brought thousands of Haitians into the streets and prompted a tough response from Army troops wielding clubs and firing tear gas.

An administration official said the United States earlier this month sent Haiti $500,000 worth of riot equipment, after Haitian officials complained that they had only out-dated shotguns in their arsenal. The equipment included gas masks, tear gas, rubber bullets and two-way radios. The official said Haiti was entitled to the aid under an existing military assistance program.

Yesterday's move came as the first U.S. shipment of emergency food aid arrived at Haitian flour mills. About 14,400 metric tons of wheat, about a month's supply, was sent to head off an impending shortage.

When he took over as head of the original six-member council, Namphy pledged to move Haiti toward the first democratic elections the troubled island has known since 1958, when Francois (Papa Doc) Duvalier began a brutal dictatorship that lasted two generations.

But Namphy has not set a date for the elections, and many Haitians and foreign observers doubted that the career military officers in the new government would be eager to hand over power to civilians any time soon.

Still, in the first weeks, Namphy impressed the skeptics by announcing plans to permit free labor unions, political parties, freedom of the press and an assembly to draft a new constitution.

In announcing yesterday's government shake-up, Namphy said, "Because of the climate of unrest and uncertainty reigning in the country, the armed forces of Haiti decided to restructure the National Government Council after the resignation of some of its members."

Besides Gourgue, who resigned Thursday, the three who were dismissed yesterday were civilian Alix Cineas, a holdover from past Duvalier Cabinets, and Cols. Max Valles, and Prosper Avril, both long-time Duvalierists.