school shootings,mass shootings,gun massacre,parkland,florida school shooting,columbine,sandy hook,guns,gun lobby,nra,gun control,gun lobby and congress,crime justice,parkland school shooting,active shooter lockdown,school entrance door,first pair of shoes,first tooth milestone,bullet damaged door,gun violence epidemic,nra influence,school safety failure,mass shooting response,columbine anniversary,sandy hook legacy,congressional inaction,gun lobby pressure