In 1927 a massacre took place at the Bath School in Michigan. In that attack, 38 elementary school children where killed, 2 teachers, 4 other adults and the bomber himself. In addition, least 58 people were injured.
Several things need to be noted.
1. The world always has and always will contain disturbed individuals.
2. They often look like the rest of us.
3. When a disturbed person has locked in on doing damage, they will be flexible in how they do it. If they first want a gun and cant get one, they get a bow or a knife as we have recently seen. Some might choose a bomb.
4. A shooter, bow or knife wielder can be stopped by a trained person with a gun.
5. A bomber is not so easy to stop. Bombs can be hidden, have timers, wireless detonation, etc.
6. The law abiding are the only ones that feel the pain of governments trying to legislate safety.
Confusing criminal acts with acts of mass murder like happened in Newton is a cop out, there is little connection between the two. Criminal killers function toward a definite goal: theft, paid assassination, singular murder etc while mass murderers seem to have no goal except death to as many as they can do and sometimes coincident suicide.
In the US, there is never a connection made between a few factors, besides the availability of guns, such as the prevalence of mind and mood altering drugs used both in our schools and in our social culture, violent video games, single parent households, dysfunctional family units, lack of morals and ethics taught in our schools (that would be judge-mental and we cannot have that) and movies that glorify mass mayhem. All these things are connected in my view and to single out just one as the culprit is myopic.