ATLANTA (AP) _ Four hostages walked out of a federal prison held by Cuban inmates early Sunday as cheers erupted from a nearby hillside where hostages' families have kept a vigil, although authorities gave no reason for the release.

Prison officials identified the released hostages as Walter Cassidy, Carl Gates, Lawrence Greer and Manuel Echevarria. There was no immediate report on their condition.

Earlier, Cable News Network reported that the Cubans had offered to release some hostages in exchange for telephone service. Some families of inmates said they received phone calls from the detainees shortly afterward.

Two new fires broke out at the prison Saturday, and one refugee told fellow inmates he was ready to kill some of the 94 hostages. Later, a spokesman for the inmates said they were ready to die before dropping their demand for freedom.

U.S. Justice Department spokesman Thomas Stewart said the blazes erupted Saturday night in the prison segregation building and in the education building. Firefighters were hampered by the fact that the burning buildings were inaccessable from the areas not controlled by the Cubans, who took over the prison Monday.

''Among the inmates there are people who want to destroy the entire prison,'' he said. ''That's one of the many factions we're dealing with.''

The segregation building formerly was used to house inmates held in solitary confinement, Stewart said. Firefighters were battling the blaze from a position away from the building because it was in an area under Cubans control.

Stewart later reported a second fire in the education building, near the prison factory that burned when the Cubans revolted Monday. He said firefighters probably would not be able to pour water on that fire because it was too far inside the complex to be reached from outside the wall.

Stewart said early Sunday that talks between the detainees and government negotiators had resumed by phone after earlier problems with the telephone service.

Unidentified detainees took turns reading a statement of demands in Spanish and in English over the two-way radio late in the evening, basically repeating demands they had made in negotiations with prison officials earlier in the week.

The detainees demanded due process rights and individual judicial reviews of the their cases; dissolution of the immigration agreement with Cuba that prompted Monday's riot; treatment for the mentally ill detainees; and no retaliation or prosecution for damages caused in the insurrection.

Outside the prison walls, detainees' relatives told reporters that the broadcasts started after a Spanish language radio talk show apparently revealed to the detainees that the news media were monitoring their two-way radio transmissions.

In their statement, the Cubans vowed ''that we will abide by our promise to release immediately all the hostages after the United States government guarantees and signs (a document meeting their demands) in front of a live television camera that will include national and international coverage.''

''We will die before we give up our hope for deserved freedom and liberty,'' the man reading the statement said.

One hostage, identified as prison guard Julio Pineiro, said over the two- way radio, ''I'm doing fine. The Cubans are treating us well.

''Let's keep these negotiations going,'' he added. ''They want their liberty. I think the situation they've been under these past two years, we should be as fair to them as they have been to us under these conditions.''

Federal officials had shut off water to the prison Friday and said there would be no food shipments to the rioting inmates. Food supplies within the prison, however, could allow the inmates to hold out for several weeks. Authorities reported no progress in negotiations.

An inmate was heard Saturday to say in a two-way radio conversation monitored outside the prison, ''We are asking for water.'' Water pressure in the prison has dropped since the inmates damaged much of the facility in Monday's takeover.

Stewart said that judging from the extent of the fire visible Saturday evening, inmates must have moved flammable materials into the segregation building, which is built of non-flammable materials. It was the first fire in the complex since the blazes that broke out during the takeover Monday burned themselves out on Wednesday.

Earlier in the day, journalists saw inmates moving mattresses and water from building to building in the prison compound. Stewart said he was unsure how long the water remaining in the system might last the inmates.

The 1,100 Cubans began rioting in protest of a plan to deport many of them to their homeland. One person has died in the rioting and at least 21 have been injured.

One inmate was stabbed early Saturday in a fight with another Cuban, authorities said. He was treated at a hospital, then returned to the prison, they said.

Arguments among other inmates were heated in monitored radio conversations.

''You stay over there,'' one inmate told another, presumably of a different faction. ''I've got the rednecks (Americans) in here. We'll kill them all. We all have our knives out.''

The conversations simply ''could involve machismo'' on the part of the Cubans, Stewart said. There were no reports of violence against the hostages.

In another radio conversation Saturday, one Cuban was heard to say in Spanish, ''Everything's OK.'' Another replied, ''No, nothing's right.'' And an inmate using the code name of ''Charlie,'' identified by federal officials as the leader of one faction, complained, ''What the hell's going on here? I'm trying to sleep.''

Charlie also was heard to tell his fellow inmates, ''Do things slow; everyone is very nervous. Do things right and with a cool head.''

Inmates soldered shut a door that had been a major passageway, ''so we can't get to you, and you can't get to us,'' according to a monitored conversation between Charlie and other inmates. It was unclear whether the action was aimed at auoing to check on the body and, ''About the time he got there, the body got up and walked away.''

No face-to-face talks have been held since Thursday.

''Any time they ask us for something, they have to be prepared to give something,'' Stewart said. ''Primarily, what we are interested in getting in exchange is hostages - and we have seen no hostages emerging.''

U.S. Bureau of Prisons Director Michael Quinlan said, ''We do have discussions, and that's a very positive sign, and we want to continue to develop those discussions and to refine all the details of the issues.''

But he said that the chances for an end to the stalemate were better at the Federal Detention Center near Oakdale, La., where Cuban inmates were holding 26 people hostage.

Federal officials have complained that the Cubans' lack of organization has hampered negotiations. The inmates have begun using a public address system to communicate with each other inside the penitentiary.

The inmates are being ''encouraged to focus their demands,'' Stewart said, although he continued to refuse to discuss the negotiations in detail.

''We think, at this point, that we know who the leaders are at Atlanta,'' Quinlan said at a news conference Saturday in Washington.

Three more Cubans surrendered to authorities, Stewart reported, bringing to 272 the number who have given themselves up since the rioting began. About 20 of the prison's 194 American inmates remain inside.