The shooting in Las Vegas is the worst in US history.
It also seems to reflect significant planning and a desire to inflict maximum damage – automatic or modified semiautomatic weaponry, a high vantage point and possible prior surveillance, and the shooter chose the time and location of the shooting carefully.
To our eyes, the shooter Stephen Paddock also appears to be very experienced with firearms. This would be consistent with the many weapons found in his hotel room as well as the possibility that he might have modified a semi-automatic rifle rather than buying an automatic outright.
This doesn’t sound like a typical case of someone who “snapped”. It required planning and logistics and was calculated to kill many people in a scenario where they could not escape.
Political motivations should not be ruled out on this one until an alternative motive has been established. We don’t have the info that Las Vegas police do, but this attack has many characteristics of politically-motivated terrorism.
Edit 9:35AM: We think the most likely scenario is that Paddock was able to acquire a fully automatic rifle due to Nevada’s loose gun laws, rather than modify a semi-auto. Time will tell.