Mainly from their own actions...
IIRC the biggest killers of US cops tends to be things like car accidents (I think outside or police work on it's own beats murdered officers), heart disease, and funnily enough when the US police decided that covid wasn't a thing, Covid killed several more times as many officers as any other cause.
From memory in terms of the chances of dying at work US policing is way down on the list, let alone of them dying of "harmful intent" or "homicide" (IIRC it's not even top 20 many years), I seem to remember for a long time the likes of Taxi drivers and Pizza delivery drivers, and store clerks had a higher chance.
To give some perspective your "agricultural" worker on about a third of the average salary and usually without any of the "death in service" benefits is considerably higher on the list.