The invention relates to a hybrid inflator especially for a vehicle safety system, comprising an igniter (10), a combustion chamber (16) including a propellant charge (18) which is separated from the igniter (10) by a first bursting element (14) held by a bursting element holder (13), and comprising a compressed gas tank (20) filled with compressed gas and having at feast one discharge opening, the discharge opening being closed by a second bursting element (24) and the compressed gas tank (20) being fluid-communicated with the combustion chamber (16) so that the compressed gas surrounds the propellant charge (18). The invention excels by the fact that the bursting element holder (13) at least in portions delimits an ignition chamber (30) containing a booster charge (15), wherein a shock wave (SW) for opening the second bursting element (24) can be formed only when both the igniter (10) and the booster charge (15) have been ignited and, respectively, activated. The invention further deals with an airbag unit and a vehicle safety system comprising said hybrid inflator or said airbag unit. Moreover, the invention states a method of forming a shock wave within a hybrid inflator.