RIP to the victim
People here seems to ignore two thingss.
Muslim Extremistism, or what you called "Brown Terrorist" is no where near the number of terrorist incident report by the FBI per decade.
Have you heard of Cesar Sayoc? He is a Hispanic Anarchist terrorist which mailed 11 pipe bomb to federal and political office last week, chances are you probably never even heard of him unless you follow US local news.
Or name like Jerry and Joseph Kane, Joe Stack and so on, you probably don't know all these people but they are all afflicated to domestic terrorism. Just that becuase they didn't kill many people, you probably never heard of them internationally.
Muslim Terroristism is on the rise, but still no where near the level of Domestic Terrorist group such as Anarchist movement and anti-government movement.
Second thing I want to say is that the right to bear arms is not an issue here, many country allowed what US allowed in term of procession of weapon, many more country have a even lax law than the US, but you don't see them (Canada, Sweden, Norway, France, Netherland) having mass shooting event like America.
The underlying problem with this is the people, not the guns, you can take away the guns and as long as these people and their grievance and their problem are not going away, you will still have Mass Casualty Event
Focus on the people, not the gun.