As had already been pointed out earlier in many public discussion threads, such incidents are rare. The fallout, though limited, is very profound in the lives of the individuals affected. It seems unlikely that gun control, or 'bullet control' as a recent article in The Atlantic proposes (have not bothered to read it, might just be satire) get to the root to even be practically effective.
I was part of school, which then was considered to among the best (around my class both academically and in sports) in a city of over 10 mil, which perhaps had the best educational infrastructure in India. When I was in 9th standard, it shocked the staff when the 'geeks' applauded one of the 'ruffians' who went into the staff room and held a knife to one of the teachers and asked him to lay off insulting us. While I do not have clarity on anger or frustration, or its causes, I do wonder what triggered the rage.
Should our schools be prisons or should we incur the impossible cost of trying explain to our children why we should not fear?