Igor Kurdin , a former '' Typhoon '' - class submarine commander and the current head of the St. Petersburg Submariners Club , attributed the high casualty count to the presence of a large number of civilian specialists on the submarine at the time of the accident . Seventeen of 20 people who perished in the accident were civilians . He noted that civilian observers would be untrained in the proper response to the release of the boat 's firefighting gas , which would be preceded by a specific light and sound signal , after which all on board are supposed to put on oxygen masks to allow them to survive during the 30-minute period required to ventilate the compartments before they can be reopened . In addition , because the accident occurred at 8:30 pm , many of the civilian specialists and crewmen would likely have been asleep , and unable to don their oxygen masks in time . The accident is the country 's worst since the controversial August 12 , 2000 , sinking of the Russian nuclear submarine '' Kursk ''
Kursk
Kursk submarine disaster
K-152 Nerpa accident