Mass shooting in Las Vegas

Wife and I have friends/relatives in LV, so she was on the phone as soon as she woke up and turned the radio on... nobody we know was at the event, although one person had a flight delayed when the airport was shut down due to being in range of what was happening at the concert venue

Watching the news and listening to the discussion, we have to agree with what we're hearing... just how do you prevent this kind of thing with SO many places where people gather?

There are already people who complain that the US (the entire world) is becoming a police state with cameras everywhere and tracking of everything on the Internet... and then this happens and there are calls for even more surveillance