I've been there. Nice little place.
The same questions arise. Where did he get the guns? How did he get the guns? Were they bought from FFL holder dealers and were background checks conducted? Let us remember that the level of homicide employing guns has been steadily falling in the US for the last 25 years. The people doing the mass killings are insane. Did this man have a criminal or mental health record?
Why do we want to keep the right to own and bear arms without the government knowing who has them and where they are? Read what Madison wrote of that?