A gas generating system (24) is provided including a gas generant container (34) and an initiator (28). The initiator (28) is positioned exterior of the gas generant container (34) so as to enable fluid communication with the container (34) upon activation of the initiator (28). A gas generant composition (32) is positioned within the container (34). The gas generant container (34) may have sufficient rigidity to maintain a predetermined shape prior to positioning of the gas generant (32) therein, and is penetrable by combustion products resulting from activation of the initiator (28). A seatbelt device (150) and a vehicle occupant restraint system (180) incorporation a gas generating system as described herein are also disclosed.