Described in this specification is a shock tube initiator that is suitable for one, two, or more shock tubes. The initiator has a number of safety features to avoid inadvertent firing of the shocking primer. Features include a rotary safety and a firing plunger that selectively interfere with the firing pin. There may further be a safety pin for fixating the rotary safety onto the housing of the initiator, so users must deliberately remove the safety pin before the rotary safety can be disengaged.