Obviously there are horrible situations like what you saw and they're not to be minimized nor is any job where you're dealing with the public in often their worst moments.
When it comes to pure on-the-job life threatening danger though- roofers and fishermen and truck drivers and even landscapers are more likely to be killed at work than a cop.
It's not all about being killed on the job,,,,,,,there's a sht ton more they deal with than just the number that actually die. You are literally skating around every other aspect of their job to reach a point where you came up with those four occupations to compare with what cops deal with during their careers.