An igniter 40 activated blocking device 10 blocks a fluid line 4 adapted to carry fluid. The blocking device 10 has a housing 30 disposed about the fluid line, a piston 20 housed in the housing, and an igniter 40 that when activated propels the piston 20 to block the fluid line 4. The igniter 40 generates a shock wave to move the piston 20 to block the line. The piston 20 crushes or squeezes a portion of the line 4 to close the line.