When I was in 7th grade, a kid revealed to a few of us that he was going to come to school the next day and kill a few dozen jocks, preps, bullies, etc. He warned us to stay home.
Of the group he told, I was the only one to rat him out. I spent the rest of the day behind closed doors answering questions, etc.
They ultimately let him come to school then tackled him coming off the bus. He was armed and had was well equipped to kill as many people as he wanted.
He communicated thorough someone else that he would find and kill me. I still wonder if that crazy ***** is going to come knocking someday.
I've never really discussed that with anyone. Initially I felt like a tattle/narc. Now I realize I probably changed quite a few lives that day.