Russian officials say one of the hostages held in a Moscow theater taken over by Chechen separatists has been killed.
A Russian official from the Federal Security Service confirmed that a woman has been killed in the hostage crisis.
Russian media showed pictures of a body being carried out of the theater on a stretcher, covered with a piece of cloth.
The official, Sergei Ignatchenko, said the woman was killed Wednesday while attempting to escape. He did not say how he knew the time or circumstances of her death.
Shortly after her body was brought out, several explosions were heard in the area of the theater, but their origin was not known.
Earlier Thursday, the heavily armed Chechens released a few hostages, after threatening to blow up the theater, if Russian police tried to storm the building.
Russian President Vladimir Putin blamed the incident on what he called the same criminals who have sown death and destruction in Chechnya.
President Putin said the main aim of the security forces must be to secure the hostages' release with maximum safety.
The hostage crisis began Wednesday evening, when about 40 heavily armed men and women broke into a theater in southeastern Moscow.
Many of the hostages have used their mobile phones to contact the media. They say they have had little to eat, and are exhausted from the long ordeal.
Russian lawmaker Irina Khakamada entered the theater where the hostages are held, and spoke with some of the hostage-takers. She later spoke with Russia's TVS television.
Ms. Khakamada said the hostage-takers did not let her see the hostages, but she was told there are some people in bad condition who need medical attention.
Ms. Khakamada said the hostage-takers gave her demands that she was taking to President Putin at the Kremlin. She did not say what the demands were.
Witnesses say, when the gunmen broke into the building, they fired automatic weapons, and demanded an end to the war in Russia's breakaway region of Chechnya.
Separatists have been fighting Russian troops for the past three years in Chechnya.
A number of foreigners are among the hostages. Representatives from many of the embassies in Moscow, including Austria, Germany, Britain and the United States, were on the street near the theater Thursday, and there were reports that more foreigners might be released, although this could not be confirmed.
President Putin has also canceled a trip he was scheduled to take this weekend to Mexico to attend the Asia-Pacific summit.
In 1999, a series of apartment bombings killed about 300 people. Russian officials blamed the bombings on Chechen separatists and cited the bombings as a reason to send troops into Chechnya.
This is the second military campaign Russia has waged in Chechnya since the fall of the Soviet Union. Russian forces invaded Chechnya in 1994, only to withdraw in 1996 in a harsh defeat.