The invention relates to a gas generator (10), in particular for a vehicle occupant protection system, comprising at least an igniter (15) and a combustion chamber (17) containing a pyrotechnic solid fuel bed (18), wherein a spring (30) is arranged in the combustion chamber (17), which spring can be elongated in the direction of an end (22) of the combustion chamber (17) remote from the igniter (16) by a gas flow produced when the gas generator (10) is activated. According to the invention, the spring (30) has a plurality of spring segments (31, 32, 33) having outside diameters (Q1, Q2, Q3) of different size.