Moscow's chief medical officer says all but one of the 117 dead hostages from the Moscow theater siege died from gas poisoning.
Dr. Andrei Seltsovsky says nearly 650 people remain hospitalized, including 150 who are in intensive care and 45 who are in very serious condition. This is the first time that the Russian authorities have identified the cause of death of the victims.
Special forces pumped a mysterious gas into the theater early Saturday to incapacitate the Chechen rebel hostage takers and free the captives. The Russian government has refused to give details about the type of gas used.
Meanwhile, Moscow hospitals began releasing some of the hostages, but most will be kept for further treatment.
Russian President Vladimir Putin, who visited some of the injured, declared Monday as a national day of mourning for the dead.
Mr. Putin apologized for the loss of life, but said the the rescue mission was necessary to show that Russia -- in his words -- "cannot be forced to its knees."
Security officials insist the death toll would have been much higher without using gas, because the hostage-takers had threatened to blow up the theater if troops forced their way in. The militants were wired with explosives strapped around their waists.