Not everyone who is picked up by an ambulance leaves the vehicle alive. I've seen what fire can do to a person's body. People can end up in an ambulance for disturbing reasons. One of the worst happened to be the result of domestic violence. Gunshot wounds aren't as "clean" as people portray them in fiction, either. That was another shock.
It's not a field for the faint of heart. There are resources to help people in this field, and there are people who have been at it longer than I have. But I think three years is long enough for me. And the scariest part is that the people who taught me have seen far worse than I have.