We have actually trained thousands of first responders, including firefighters right across the country, for that specific reason. We use a self-assessment tool that was formerly called the Road to Mental Readiness and is now called The Working Mind. It addresses the issue of first responders having to deal with huge tragedies, including death, on an ongoing basis.
One police officer told me it saved his life. He went home to his wife and said, “I believe I'm in the orange category.” She said, “No, you're not. You're in red.” He got help and it saved his life. It was because of problems dealing with his work situation.