They need to have a gun amnesty
They need to look at school and college security, nobody gets in without going through 3 security doors and metal detectors ( or similar heightened security methods)
Only farmers/ people at risk of bear/cougar attacks are allowed to own a basic rifle or shotgun
Only police may carry firearms ( eventually tailing off to only armed specialist response units when majority or illegal and legal firearms are melted down)
Anyone found with a gun who doesn't carry a valid licence faces a mandatory custodial sentence.
Anyone who qualifies for a gun licence must pay for an annual psychological evaluation at their own cost or have licence revoked.
If you want to hunt then only licenced hunting allowed by proper companies.
.........
I think with tweeks the above is what I think should be done.