I'm not sure how to define "witnessed or personally experienced"...

In the witnessed category: driving by the dead body of a motorcyclist who had been killed by a drunk hit-and-run driver. But I didn't know at the time what had happened except that there was a body that was probably dead.

Re. personal experience, I have to go with a bad trip on hallucinogenic mushrooms I had in college. But "miserable" is a better word than "scary."