Kyle is possibly guilty of carrying a firearm under age 18 (if he had a safety class this apparently doesn't apply). He is also guilty of a curfew violation, along with everybody else there.
However, he also has a basic right to self defense, and the video and witness accounts clearly establish that each of the three people he shot posed a risk to him of death or serious bodily injury:
1. The first casualty can be seen on video attempting to start an altercation with other members of the armed group (shoot ME !@*!), then can be seen on video chasing Kyle after Kyle attempted to put out a he and his group started, with a fire extinguisher. He is pursing Kyle and that makes him the aggressor, not Kyle. He throws something that appears to be on fire at Kyle. He catches up to Kyle and attempts to grab his rifle (which is further illegal as he is a convicted felon and sex offender). The witness account states that they seperated and as the casualty grabbed Kyle's weapon a second time, he was shot and killed. Kyle himself can be seen on video trying to render aid and calling 911 to report the shooting and request medical. Then the mob starts yelling "get him" and chasing him down the street.
2. He runs away and is hit in the head by a pursuer (aggressor) and does nothing. Not until he falls down does he take another shot. He is kicked in the head by one guy. The 2nd casualty attacks him with a skateboard, attempts to struggle for the rifle and is dispatched.
3. The 3rd casualty was standing over him with a firearm when shot.
These facts will provide an open and shut case of self defense.