We know that states with the most gun laws tend to have the fewest gun deaths. So the notion that gun laws don't work, or just will make it harder for law-abiding citizens and criminals will still get their guns is not borne out by the evidence.
We know that other countries, in response to one mass shooting, have been able to craft laws that almost eliminate mass shootings. Friends of ours, allies of ours - Great Britain, Australia, countries like ours. So we know there are ways to prevent it.