All public schools need to develop and implement a practical escape plan in the event of a shooting. Each teacher needs to be assigned a role that is fitting to his or her skill set. These drills need to practiced just like any other fire or earthquake drill. They should be conditioned into the students memory just like a fire or earthquake response drill.A Seperate signal should be used to identify that this emergency is NOT a fire or earthquake and should signal a rapid response team or SWAT unit.
Teaching kids to hunker down and wait for the cops is NOT a proactive plan to prevent the loss of life. Hunkering down is only effective if you have a means of defending yourself.
Restricting firearms ownership or otherwise removing the rights of law abiding citizens will not be effective.