"Kursk" carried a potassium superoxide cartridge of a chemical oxygen generator; these are used to absorb carbon dioxide and chemically release oxygen during an emergency. However, the cartridge became contaminated with sea water and the resulting chemical reaction caused a flash fire which consumed the available oxygen. The investigation showed that some men temporarily survived the fire by plunging under water, as fire marks on the bulkheads indicated the water was at waist level at the time. Ultimately, the remaining crew burned to death or suffocated.