I’m actually surprised that both kids died.
He may not have been trying to kill anyone but just shot to scare them off and inadvertently fatally wounded them.
Also not a smart strategy. You either shoot to defend your life or others life, or you don't shoot. Shooting to warn can result in an accidental death and the shooter is now responsible.
We should all have the right to defend our lives and families, but take it seriously if you are going to do so. Understand the laws in your area and train scenarios so you already know what the 'best' response is in most circumstances.