Oh, I forgot the most fun part of my scenario.
After the police DO show up - with numbers enough to get the gang to leave, which is going to take a little while - they're going to confiscate any weapons in the home. Oh, did I say confiscate? I mean, they're going to collect evidence. You'll get 'em back, after the DA has tried charging you with manslaughter or murder. Usually they'll start with murder and try reducing it to manslaughter. You might go through 3 or 4 DAs before you get one who's willing to try taking you to court so he can make a name for himself.
This state completely disgusts me sometimes.
The GOOD thing about California's self-defense laws is that you're presumed to have a reasonable fear for your life if someone unlawfully and forcibly enters your home. You don't have to see a weapon, you don't have to hear a threat, you don't have to retreat or give any warning, you just shouldn't shoot them in the back. In a home-defense situation, the burden of proof is shifted to the DA, who has to prove you did wrong. Apparently, if you shoot someone in self-defense on the street, it's YOUR burden to prove you needed to pull the trigger.
Also in CA, the law says if someone is TRYING to gain entry to your home and is bent on harming you, you don't have to wait for them to come inside.
Also note that opening my front gate (you have to reach over a nearly 6 foot gate to unlatch it) may actually qualify as a forcible entry. I want to research it a bit more, but I'm fairly sure I could shoot an intruder in my front yard and be in good shape legally.