The shooting took place less than two seconds after the police car pulled up to the boy. He was carrying an unloaded pellet gun -- a device also known as an air gun.
The airgun blasts from seismic surveys can mow down a swath of zooplankton, the tiny creatures near the base of the food chain, or can deform scallop larvae while they're developing.
If you're talking about tranquilizer darts, you're probably referring to the kind that are shot out of an air rifle using compressed gas, though they can also be fired from crossbows or blowguns.