What Ms. Olsen describes is a fear. Not a fact, a fear.
To deal with that fear, one can get training. One can train in first aid. One can train on the safe handling of firearms. One can train on how to take cover. There is even active shooter training for the school and workplace.
We train, so that if the worst happens, we won’t have to think about what to do, we just do it. And in doing something, we don’t have time to be afraid.
As for the answer to this violence, allow me to point out that statistically we have never been safer from this sort of violence. The reason it makes the news is because, like airplane crashes, it really is unusual.
The solution to fear is knowledge, not laws, or expecting the rest of the world to accommodate your fears. Then, if there is anything that can be improved upon, run it up the flag pole and see if anyone salutes.