During the 2002 Moscow theater hostage crisis , Russian special forces used an unidentified gas ( thought to be 3-methylfentanyl or another fentanyl variant dissolved in halothane gas ) in an attempt to induce sleep in both hostages and terrorists . Many of the hostages and terrorists ( including all of the suicide bombers ) were anesthetized , but some terrorists donned gas masks and thus were able to avoid the effects of the gas . Because the agent used was a potent Fentanyl derivative ( a synthetic opioid ) , it causes respiratory depression and ultimately respiratory failure if administered in high enough dosages . The central nervous system effects , such as anesthesia and respiratory depression could have been reversed by an opioid antagonist such as naloxone , which is stocked by hospitals and most ambulances . However , because the Russian authorities did not release any information regarding what type of agent was used , medical professionals were unaware that an opioid had been used during the rescue attempt and thus were unable to administer the antidote which could have saved most hostages . Approximately 700 hostages were rescued , while 130 died from exposure to the gas . All the terrorists were ultimately killed by Russian forces through some combination of gas exposure and gunfire
Moscow theater hostage crisis
Moscow theater hostage crisis
Non-lethal weapon