The K-152 Nerpa accident was an incident that occurred aboard the Russian submarine K-152 Nerpa on 8 November 2008, which resulted in the deaths of 20 people and injuries to 41 more. The deaths and injuries were caused by an unsanctioned release of fire suppressant gas inside the submarine during a submerged test run during the vessel's sea trials in the Sea of Japan. The gas caused victims to die of asphyxiation or suffer frostbite in their lungs. The incident was the worst Russian submarine disaster since the Kursk sank in 2000. Three of the dead were military personnel and the rest were civilians from the Vostok, Zvezda, Era and Amur shipbuilding yards who were members of the acceptance team.