A chlorate candle: "used to produce oxygen, exploded during a training exercise.
" <---being cited as the culprit.
Conventional weapons, nuclear sub. Two dead, one injured...(currently in hospital, in Anchorage, Alas.)--Apparently, these oxygen generating devices are shot with a .22, in the case of this sub.
In the case of the ValuJet Flight 592, leaving Miami to Atlanta "All 110 on board ValuJet Flight 592 died."
"On 23 February, 1997, during the exchange of an air filter on the Mir space station, a chlorate candle spewed a torch-like jet of a molten metal and sparks across one of the space station modules, burning for 14 minutes and blocking the escape route to one of the Soyuz spacecraft. There were no injuries."