All but two of the 117 hostages so far confirmed dead in the Moscow theater siege died of gas poisoning, the city's top doctor said today.
Mr Andrei Seltsovsky, chairman of the health committee of the city of Moscow, said only one of the around 800 hostages had died from gunshot wounds when elite troops stormed the musical theater early yesterday.
Asked what the others had died from, he said: "From the effects of the gas exposure."
One man had been shot dead during the operation to free the captives. The second to die of gunshot wounds was a woman shot while trying to escape when the theater was seized by around 50 Chechen guerrillas on Wednesday night.
Mr Seltsovsky told a news conference that 646 of the freed hostages were still in hospital, of whom 150 were in intensive care and 45 were "in a grave condition."
The unidentified chemical was so powerful that the Chechen suicide fighters had no time to detonate the explosives strapped to their waists.
Sergei (36) who declined to give his family name, told Reutersnews agency after he was released from hospital that the gas had smelled slightly bitter. Chemical warfare experts say nerve gas often smells of bitter almonds.
London-based security expert, Mr Michael Yardley, said he believed the gas used was BZ, a colorless, odorless incapacitant with hallucinogenic properties, first used by the United States in Vietnam.
He said the symptoms displayed by the hostages in Moscow - inability to walk, memory loss, fainting, heartbeat irregularities, sickness - all pointed to BZ. According to the US army the side effects last 60 hours, Mr Yardley said.
"The Russians wouldn't want a big shout about it because it (BZ) is just the sort of stuff they are not supposed to have," he said. "It's not specifically banned, but...it is in a sort of grey area."