I think any gun outside of hunting guns should be banned except for law enforcement/military. What purpose does an assault rifle serve outside of killing another human being? We shouldn't have stuff like this in America, let the military and the police force have them and use them for appropriate purposes.
But I digress, we have over 100 mil illegal weapons out there and 90% of those that have them are not going to turn them in. We could ban all weapons but they will still be out there and sold to the highest bidder who wants to commit a massacre.
I really don't see what we can do about it, taking away the only way people can defend themselves is going to be tough but again none of these mass murders had anyone to shoot back in that vicinity until the other day but it was too late, perhaps the hero avoided more slaughter no one knows, but we do know if someone can shoot back, they will.
A very huge conundrum, ban guns, illegal weapons would be even more widespread or mass killings move on to even more dangerous weapons like improvised bombs from material you can get at Wally world or Ace Hardware.....or drive a Hummer on the street, which is even more dangerous than a moving van.
In the end the murderers or terrorist are getting the last laugh because we are still fighting over what should we do and in the end, nothing will prevent things like this. Only vigilance and tattle-telling can brunt it.