I've actually been quite lucky in that I haven't actually witnessed too many very traumatic things. I've been through things that felt traumatic but likely wouldn't be, compared to other people's experiences.
I was a part of a large crowd that witnessed a plane crash at an air show once. That was shocking. It just fell out the sky pretty much and exploded on the ground. It was worse because I think his wife may have been in the audience. In a way, it was similar to emotions felt here sort of. In that he died doing something he chose to do, that he must have realised carried risks. He obviously didn't intend to die but, he must have known it was a real possibility.
I remember being very young and on a school trip to a museum. A staff member was sitting on a big flight of concrete steps with people all around holding her head. I think she must have fallen. I found that very upsetting at the time.
We also went to Ypres on a school trip and visited a museum about the war and concentration camps. I think anyone at any age seeing piles of emaciated bodies being bulldozed into huge ditches would feel sickened. Plus, the sea of tombstones was really upsetting.
I also feel like I witnessed what I would call a sexual assault on one of my friend's young brothers by his Mum. I truly didn't know what to do or think at the time. I just kind of sat there dumbfounded trying to observe and take cues by how her family reacted. To clarify- it wasn't rape or anything. She sort of flipped him upside down and grabbed his nuts and made some comment on how he enjoyed it. I just felt so uncomfortable and sorry for him. Obviously, it was really embarassing for him.
I think some people like to shock others. Someone I knew who was older seemed to deliberately reveal their self harm scars. I was very young at the time so, that felt pretty distressing.
