In years past police were issued a 12 gauge shotgun and the ammunition was 00 Buck Shot.
00 buck shot is NOT bird shot, it has a diameter of 0.36".
According to Winchester their loads leave the muzzle at 1,325 feet per second with 9 pellets in each load.
00 buck shot can be lethal at 100 yards.
The articles do not say what type of ammunition was used in the department-issued shotgun.
If it was buckshot the officer should be out of a job.
I would almost guarantee the PD has a policy or ROE document that Barney Fife can hide behind, no matter what ammo he may have used. But that doesn't stop this from being one of the more wanton and stupid applications of police power that I've heard of in a while. In my experience, rural cops are more sensitive of property owners rights than this. Unless there serious "in progress" situation nearby they are likely to knock politely and ask permission to be on your land. Nobody should want an armed confrontation, least of all the PD.