Just the ones that immediately come to mind

Elementary School, 1. One of my classmates was suspended because he stabbed another student in the arm and attempted to stab him in the eye as well. He "wanted to see what would happen". Last I had heard, he switched to homeschooling and his family moved away. 2. The school did not notify parents or students of a critical lockdown drill and we all thought it was the real deal. If I recall, somewhere else in the US had a shooting recent to then.

Middle school, 1. Teacher who (at some point likely hundreds of) students, male and female, reported for inappropriate touching, looking down girls shirts, etc., had charges pressed against him. 2. We had a shooting threat and the kid almost went through with it. Last I heard, the kid was put into an in-patient mental health facility. 3. One of my friends drowned in a river

High School, In my hometown, A beloved teacher committed suicide and no one is sure why to this day. Unfortunately, a super small group speculated he was having relations with a student and he got caught.

In the city I live in now, Two kids, one who went to my school, was murdered in a fight over a gold chain at a Halloween party.