Norway had one very famous case in its history and passed strict gun legislation after that. No cases since. Thanks for proving my point.
As for Mexico, is that what you really want to compare the US to? Even then it is not even close.
19 Countries with the Most School Shootings (total incidents Jan 2009-May 2018)
United States — 288
Mexico — 8
South Africa — 6
India — 5
Nigeria & Pakistan — 4
Afghanistan — 3
Brazil, Canada, France — 2
Azerbaijan, China, Estonia, Germany, Greece, Hungary, Kenya, Russia, & Turkey — 1