If people wanted to kill they will find ways on how to kill. Those people might be taking drugs or have watching too much crime movies. To think that night clubs have security guards, how could someone enter that premise and just shoot. That nightclub should also be held liable for that shooting incident. This could not happen if they have tight security enforcement.
It's interesting how most of the shootings like this occurs in the US, sure there are a some in the other parts of the world but mostly in the US, so maybe it's not everything in the gun laws and such, yes people will always find a way to kill someone with or without the guns.
I don'tthink guards will search you from head to toes, it's not an airline security...