Are they running away from someone with a rifle, shotgun or handgun?You can kill someone with virtually anything but how confident are you going to feel walking into a school with a hammer versus a gun? Let's be real. No 18 year old scrawny incel is walking into a school with a hammer trying to kill people...
He goes there with a military style weapon and body armor because it makes him feel God-like and makes other people fear him.
Nobody is running away from that dude with a hammer...they are running towards him to take it out of his hands and use it on him.