More than 90 hostages and 50 Chechen guerrillas died early this morning when Russian special forces pumped gas into a Moscow theater and stormed the building in a dramatic pre-dawn raid that freed about 700 captives but left most of them hospitalized.

Bodies littered the auditorium and lobby after soldiers shot dead nearly all of the heavily armed militants who had seized the theater Wednesday night and threatened to blow it up unless Russia withdrew its troops from Chechnya, a separatist republic in the south.

It remained unclear how and exactly when the hostages were killed.

Among the militants killed were 18 female suicide bombers, with explosives strapped to their bellies, some of whom were shot after they had already been rendered unconscious by gas blown through the ventilation system.

Russian authorities defended their decision to use gas, but they refused to identify the substance -- even to doctors treating those exposed to it. They insisted that none of the civilian fatalities was caused by the gas, which they described vaguely as an incapacitating agent or a type of hallucinogenic with psychotropic properties.

The raid on the packed theater came as U.S. officials were on the phone with a Chechen intermediary trying to broker the release of the American hostages, according to the intermediary, Ali Asayev. Fighting broke out just as the leader of the militants, Movsar Barayev, was issuing instructions for U.S. Ambassador Alexander Vershbow to come to the theater at 10 a.m. to retrieve his citizens, Asayev said in an interview.

In the end, it appeared none of the 75 foreigners among the hostages died, but as of late tonight Russian officials had not informed the U.S. Embassy about the condition or whereabouts of three Americans believed to have been held captive. A Russian holding a U.S. green card was reported alive and in a hospital.

As the fumes cleared and sappers swarmed into the theater to frantically try to defuse the explosives that the guerrillas had placed around the building, the extent of the carnage became clear. Bodies, unexploded ordnance and trash were strewn everywhere, and the floors were stained red. Barayev lay dead, sprawled in a bloody mess later captured on a Russian secret service video distributed to television networks here. Next to his hand was a bottle of cognac, standing upright as if placed there after his death.

One female fighter sat in a theater seat leaning forward on her hands as if sleeping; nearby, another's head had fallen back with her mouth slightly open, as if she too had simply dozed off.

Russian authorities said the Chechens had begun to kill some of the hostages, leaving the Russians with no other choice than to storm the building. The gas knocked out most of the people in the building immediately, according to authorities and witnesses, but reports indicated that at least some rebels remained conscious enough to put up a halting fight against Russian troops. Explosions and bursts of gunfire could be heard coming from inside the building as the troops made their way through broken glass doors.

Deputy Interior Minister Vladimir Vasiliyev, visibly shaken after the bloody end to the 58-hour ordeal, acknowledged that the operation "did not go easy" but said the gas attack was the surest way to handle the suicide bombers who held detonators in their hands.

"We tried to fulfill all of the terrorists' demands. The price was just too high," he said on the street outside the theater. "Terrorists constantly displayed their explosives. The building's construction is such that everyone inside would have been killed if it were to collapse."

At least some of the surviving hostages agreed with that assessment. "We were waiting to die," Olga Chernyak, a reporter from Interfax news service who was among the captives, said in a report released by her agency. "We realized that they would not release us alive. We did not believe they would let us go even if all their demands were met and troops are withdrawn from Chechnya."

Chernyak confirmed the official account that the militants killed two hostages during the night, a man and a woman.

As survivors of the crisis recovered today, some doctors were furious at the government's secrecy over the gas. "We were not told what kind of gas was used, so it was difficult for us to administer a remedy," complained one who asked not to be named. Another physician involved in the rescue effort said some of the hostages may have died by choking on vomit induced by the gas.

The United States and other countries stood by Russia in its handling of the situation. "This is a reminder of the risk to the free world that terrorists present," White House spokesman Ari Fleischer said as President Bush flew to Mexico for a summit that Putin had planned to attend, until events in Moscow forced him to cancel. The State Department agreed with Putin's characterization of the Chechen militants as terrorists. "No political grievance justifies the taking and killing of hostages," a spokeswoman said.

In Moscow, Vershbow, the U.S. ambassador, congratulated the Russians for limiting the loss of life. Asked if the operation could be considered a success given the casualties, he said, "Well, I think that when one considers that there were 700 hostages, all of whom could have been killed, then we are very relieved that the vast majority seem to have survived."

Putin thanked foreign governments for their support and again linked the incident to the global war on terrorism. "This foe is strong and dangerous, inhuman and cruel," he said. "This is international terrorism. Until it is defeated, people cannot feel safe anywhere in the world. But it must be defeated and it will be defeated."

Leaders of the separatists who have battled the Russian government for most of the past eight years, however, say they are fighting for self-determination in Chechnya and reject the terrorist label.

"The Russian raid was no less a terrorist action than what the [guerrillas] have done," said Asayev, a Chechen representative based in Baku, Azerbaijan. "The whole world is now congratulating the Russian government when they should be expressing condolences again. It proves again that the Russian government is not fighting terrorism, it is creating it."

The assault by special forces culminated a 2 1/2-day standoff that began Wednesday night when masked Chechen guerrillas swept into the House of Culture for the State Ball-Bearing Factory in southeast Moscow as the second act of the popular musical "Nord-Ost" ("North-East") was getting underway. Firing their weapons into the air, they initially took as many as 900 cast, orchestra and audience members hostage and began wiring the building with powerful explosives.

Putin never appeared to seriously entertain their demand for an end to war in Chechnya, and a parade of would-be negotiators -- from legislators and journalists to singers and a filmmaker -- left with a few hostages from time to time but otherwise empty-handed.

From the beginning, Russian authorities prepared for a possible assault on the building, sending teams of "diggers" through the Moscow sewer system to prepare for the gas attack and the entry of special forces. At 5:30 a.m., a series of explosions and gunfire bursts could be heard from the theater, as Russian troops and armored personnel carriers began moving toward the building. A flash of light lit up the street and the ground shook from the power of some of the blasts.

At 6:25 a.m., some panicked hostages tried to break for freedom, but only two made it. The bedraggled and terrified women raced out into the street, practically falling on Russian soldiers who pushed them toward safety. More explosions and concentrated gunfire followed. By 7 a.m., the crisis appeared to have ended as columns of ambulances began racing back and forth to ferry away survivors.

While the Russians said they had to move because the militants had begun killing hostages, Asayev maintained today that the Chechens had not given up negotiating. Asayev, who was in telephone contact with the guerrillas in the theater, acknowledged that they had killed a man and a woman who were seen as "spies" sent by the authorities. He claimed the two were not shot as the start of a wholesale slaughter.

Just before the Russian assault, Asayev was on the phone with Barayev. On another line, he said, was John R. Beyrle, the deputy chief of mission at the U.S. Embassy in Moscow, as the three discussed a deal to release the American hostages to Ambassador Vershbow at 10 a.m. A Putin emissary, Viktor Kazantsev, would then arrive at 11 a.m. for talks.

Just then, with Beyrle on the other line, Asayev said he heard gunfire from Barayev's telephone, which then went dead. A U.S. Embassy spokesman declined to comment on the account.

The bloody showdown at the House of Culture almost certainly will complicate efforts to bring peace to Chechnya after nearly a decade of war. Anger at Chechens has run high in Moscow this week, but so has exasperation with the war. Putin made no mention today of trying to resolve the greater conflict.

Among Russian leaders, Putin enjoyed nearly universal support today despite the heavy casualties. "There was no other option but to take the building by storm," said Mikhail Gorbachev, the last Soviet leader. Patriarch Alexei II, the head of the Russian Orthodox Church, pronounced himself "amazed at the courage" of the hostages and the special forces who freed them.

Many agreed with Gadji Makhachev, a lawmaker from a region adjacent to Chechnya, who said that in a war on terrorists, "you either have to win or surrender."

Staff writers Ariana Eunjung Cha in Moscow, Karen DeYoung in Los Cabos, Mexico, and Dan Eggen in Washington contributed to this report.

A special forces officer is visible through a hole in a poster for the show "Nord-Ost" on the wall of the theater seized from Chechen rebels. Troops who entered the theater found bodies, unexploded ordnance and trash everywhere.