No guns around Publicly accessible areas. Prevent civilians from carrying firearm(s) within at least a mile of anyplace where people gathers daily i.e. Schools, malls, movie theaters and more.
Also anybody residing within that range (a mile or more) of where more than a hundred people gathers should not be allowed to posses firearms. Having firearm(s) within range this range should be punishable by law.
If possible, classroom desks and tables should be able to resist gunshots so they can be used as shield if necessary.