Supporters of the new Sandinista-backed government in Nicaragua occupied the Nicaraguan chancery on New Hampshire Avenue NW for about an hour yesterday morning before D.C. police officials negotiated an end to the takeover.

Most of the 13 people involved in the occupation were Nicaraguans who have lived in the United States for years, often protesting publicly against the now-defunct dictatorship of Anastasio Somoza.

Several said afterwards that they believed they were taking over a building that already was theirs, though they were not acting in an official capacity for the still-forming Nicaraguan government.

After a series of scuffles between protesters and uniformed U.S. Secret Service guards at a side entrance to the chancery, police called the State Department. Officials there obtained permission from Somoza's brother-in-law and longtime ambassador to the United States to evict the protesters from the building.

A State Department spokesman would not say yesterday whether Guillermo Sevella-Sacasa, the dean of Washington's diplomatic corps, still is considered Nicaragua's ambassador. "That's a fine legal line," the spokesman said, "but we still consider him the guardian of the Nicaraguan embassy and chancery."

Sevilla-Sacasa would remain in that capacity, according to the State Department official, until the new Nicaraguan government officially replaces him.

By the time the incident was over, the two Secret Service guards and at least three of the protesters had been injured slightly, and three of the Nicaraguans were arrested on felony charges of assaulting federal officers.

Six people were in the chancery when the takeover began - an embassy secretary, her mother and sister, two Carmelite nuns asking after a fellow-nun who had gone to Nicaragua to work as a nurse and a Potomac woman seeking information about a visa.

The secretary, Rosita Corsino, went to the front door to answer the knock on the door, and found three people outside. "The people told me the embassy was taken and we've got to go," Corsino said shortly after the incident yesterday.

"They were very pacific," said Bianca Ciammaichella, another embassy secretary who arrived as the conversation in the doorway was going on. "They said, "We are taking the embassy. Be tranquil. Nothing will happen.""

At about this time, three other Sandinista supporters joined the group at the front door and entered the embassy, according to the demonstrators.

Moments later, near the embassy's side door, a series of scuffles broke out as a second group of demonstrators arrived carrying tools and two-by-four-foot boards and were accosted by officers K. S. Williams and Ronald S. Harrison.

"Officer Harrison interposed himself and asked them to identify themselves," Secret Service Agent Jim Boyle said yesterday. "One man swung a two-by-four at him and was arrested."

Four other demonstrators then rushed into the side door, which had been opened by one of their companions inside and ran towards the central area of the building, slamming an office door behind, according to the two embassy secretaries.

"Then the police came in and thery were very violent and broke in the window [on the office door] as they tried to open the door," siad Ciammaichella.

Some time later, according to Agent Boyle, Williams scuffled with one of the demonstrators inside the office and cut his hand on the jagged glass left in the door. The demonstrators, Boyle said, were trying to nail the boards to the doors and barricade themselves in.

Williams was admitted to George Washington University hospital yesterday afternoon where doctors operated on him to repair a torn tendon, a Secret Service spokesman said.

After these scuffles, scores of law enforcement officers from the Metropolitan Police Department, the Secret Service and the FBI arrived on the scene, followed by scores of news reporters and cameramen.

The police filed into the building, isolating the protesters - seven women and three men - who remained in a second-floor office. "We're in the same room with them," Deputey Chief R. W. Klotz of the metropolitan police said midway through the occupation. "They are not barricaded."

"We are in control," he added.

The occupation ended at about 11 a.m. after police officials offered the demonstrators a deal: leave immediately and no trespassing charges will be pressed.

Seven of the 10 demonstrators did so. Two others were arrested at they were assisting a woman protester who had injured her back during the takeover.

The seven emerged out the front door into New Hampshire Avenue waving red cloths as supporters across the street chanted "F - S - L - N," the Spanish acronym for the Sandinista National Liberation Front.

The three Nicaraguans arrested were Roberto Henry Vargas, 38, taken into custody at the door; Dionistio (Saul) Arana-Castellon, 30; and Leopoldo Jose Tablada, 26, arrested inside. All were charged with a felony assault on a federal officer.

They were released on their own recognizance or to the custody of their attorney yesterday afternoon, pending their arraignment today. CAPTION: Picture, Three of the women who occupied the Nicaraguan chancery shout jubiliantly as they leave building. By Fred Sweets - The Washington Post