Allowing teachers and others members of school staff to have firearms in schools would discourage would be shooters from targeting schools.
This would not only discourage school shootings but in the event of one actually happening it could help save countless lives.
As we have seen in school shootings such as in the 1999 Columbine High School Massacre in Colorado which claimed the lives of 12 students, 1 teacher and the 2 shooters.
The Virginia Tech Massacre in 2007 that claimed the lives of 33 people.
Or most recently the Sandy Hook Elementary school shooting that claimed the lives of 28 people. 20 of them being students.
Even with officers response times being fairly quick in these situations it can still give the would be shooter enough time to inflict serious casualties