At the time of this writing there was a recent holiday mission to celebrate Canada Day, hence the (temporary) addition of the Zombie Mounties!
As with all holiday Mission Zombies these are tough to take down, but if you have a good deal of Health Packs you should be fine.
Each time you take one down there is a chance of it dropping (or rather, you finding) a Campain Hat. This adds a bonus to scavenging for 60 Minutes.
(Sorry about no picture...)