The first 10 minutes are the most critical and it takes that long for police to get on scene. Well trained armed teachers is the obvious answer let them protect themselves and the kids. Willing teachers can be trained just like cops can be trained
Indeed.
Also trained combat veterans, retired FBI agents etc.
Many of these trained professionals would volunteer part of their time or could be paid.
Trying to confiscate hundreds of millions of guns in violation of the Second Anendment has not worked and will never work.