I think there is a problem, because mass shootings happen in US very often

They don't though. And what you think means nothing when it doesn't match up with reality.

And it is the law's fault.

So if you go out and stab someone, it's the law's fault? Or is it yours?

Either by being ineffective at gun control (which I agree with)

And finally the truth appears. You're not interested in honest discussion, you just want more control, despite no evidence to suggest it would work.

Five armed cops died and it took a robot with a bomb to stop him. This also weakens the assumption that Las Vegas shooter could have been stopped by the security guard, had he had a gun.

So because one circumstance, all are the same? What about the mall shooter who committed suicide when he saw a CCW holder draw on him? What about the school shooter who stopped when confronted by an armed person in a library? What about the church shooter who never made it past the armed receptionist?

And I never said it wouldn't be hard. But it's much harder when they are the only one with guns.

Cause he wasn't being so hostile

Then why are we responding to you? You're coming in on your high horse, claiming there is a massive issue and demanding Americans make changes despite not being part of the country with no research or evidence to support you. That's extremely hostile. Can't take being responded to in kind? Grow up.