As effective as your solution may be, I'm afraid Target stores are going to block the implementation (they need the business!).

Here's another (perhaps less modest) solution:

Arm everyone. It's simply an extension of the "Arm teachers to shoot school shooters" solution proposed by many (non-teacher) Republicans.

For example, as we know, toddlers are among the growing population of senseless, random shooters. Psychological testing won't work, because the toddlers can't yet complete a standard inventory. Obviously, if the parents could control the situation, they would, if only to save their own lives. But perhaps they're afraid of infringing on the Second Amendment rights of their three-year-old.

My "arm everyone" solution would furnish small arms (maybe Lugers) to toddlers so that they can shoot any other toddler who comes gunning.