They could’ve been shooting at a bird on a fence and just didn’t think about anything downrange.
The worst they could get would be manslaughter. Who’s ready to prove that two boys under ten even understood the consequences of their actions? In their world, you just hit the reset button and the target is alive again.
Regardless of their race, they’re too young to be prosecuted for anything more severe than manslaughter. And that would be only if you could prove they knew what they were doing and knew who they were shooting at.