All those examples were Asians stabbing Asians. So you would still have crime without niggers. The answer is the government MANDATES gun ownership, provides yearly training, etc.
That's similar to the Swiss model, and it's a pretty good one, but it wouldn't work in some place as large as America.
For the problem, an alternative is to purge the "asians" too.
Since "asians" is secret code for muzzies, it would be yet another benefit.
I don't really want gun-free zones anywhere. That just limits gun possession to those who would have them anyway. It makes good citizens into victims.
I can teach myself to shoot. I don't want any gov't being involved in what I do on any way.