Abstract: A gas generator for vehicle occupant restraint systems comprises an elongated housing having gas outlet openings, a sealed, rupturable gas generant cartridge positioned within the housing, and pyrotechnic gas generant contained in the cartridge. An igniter capsule mounted at one end of the housing has an exit opening juxtaposed the sealed gas generant cartridge. The igniter capsule contains ignitor material, and an initiator and initiator charge. The initiator ignites the ignitor material which expels a fireball of hot combustion products from the opening, capsules exit rupturing the sealed cartridge and igniting the gas generant charge to produce gas for inflating an air bag. A rupturable seal is provided over the exit opening of the ignitor capsule and a nozzle directs hot combustion products to the gas generant cartridge. The initiator charge is auto ignitor material for operating the gas generator if it is exposed to fire.