Deadly Siege at Moscow Theater
The Moscow theater hostage crisis, also known as the 2002 Nord-Ost siege, was the seizure of a crowded Moscow theater on Oct. 23, 2002 by some 40 to 50 armed Chechens who claimed allegiance to the Islamist militant separatist movement in Chechnya. They took 850 hostages and demanded the withdrawal of Russian forces from Chechnya and an end to the Second Chechen War.
After a two-and-a-half day siege, Russian Spetsnaz forces pumped an unknown chemical agent (thought to be fentanyl, or 3-methylfentanyl), into the building's ventilation system and raided it. At least 39 of the attackers were killed by Russian forces, along with 129 hostages (including nine foreigners). All but a few of the hostages who died during the siege were killed by the toxic substance pumped into the theater to subdue the militants.