Whenever you buy a firearm from a retailer, you are buying from a federal firearm license holder. You must fill out a federal form and pass a NICS background check in order for the sale to proceed. This is nationwide and has been in place for decades. It has a lot of false positives, too, in spite of technological progress.

Requirements for private sales have been added by some states, but this is not progress, it is overreach. A gun is just another object free people own freely.

In any emergency, the people there are the real first responders. The solution is simple. Instead of victim disarmament zones, allow teachers to carry a concealed weapon if they wish. Set a simple training standard. Defensive firearm courses abound. The risk/reward ration for violence dramatically shifts. When a citizen stops a shooting, the average casualties are a tiny fraction of when people must wait for the cops... if they even do their job in the first place.