Ballistic panels on all entry doors for school, and 10-20 feet past those, another set of doors that cannot be penetrated with bullets. Lock that dude between and wait for the cops. 87,000 new armed IRS agents, coud pay for a lot of security doors and a door monitor .
So called tranz, because the killer is and was a girl, having a psychotic break pretending to be something she could never be. Mentally ill people should not have guns, that leaves all so called tranz people out of luck.
...or a remotely wired claymore angled down from above.