"Zero tolerance was a way to up the numbers of white boys kicked out of school for offenses such as posessing an axe in the trunk of a car left over from a boy scout presentation or drawing a picture of a gun..."
When I was in high school a number of students (seniors, juniors old enough to drive) were also on the volunteer rescue squad. Some even had full crash kits in the trunks of their cars (well, maybe not jaws of life, the model the squad had at the time required a hydraulic power unit that was carried on the fire truck). Some were a bit goofs in school, but when the police radio sent a call out they were all business. These days carrying such a kit would likely land them in prison for weapons and drugs.
Of course back in those days no one played such petty games with the volunteer firemen and rescue squad. They were doing this on their own time, and you might need them someday. A rescue squad member may live on the same block, so if the call goes out at your address, the first arrival may be in less than a minute.
I will point out that the majority of the mass school shootings so far have been done by middle to upper class "white boys".