In an anti-terrorist attack on October 26 , 2002 , Russian special forces used a chemical agent ( presumably KOLOKOL-1 , an aerosolized fentanyl derivative ) , as a precursor to an assault on Chechen terrorists , which ended the Moscow theater hostage crisis . All 42 of the terrorists and 120 out of 850 hostages were killed during the raid . Although the use of the chemical agent was justified as a means of selectively targeting terrorists , it killed over 100 hostages
Moscow theater hostage crisis
Moscow theater hostage crisis
Chemical warfare