When I was in Zululand back in the mid 90s, there was quite a bit of that going on there. The farmers in the area established their own defense network, and every farm was linked by radio. At the first sign of trouble, a call for help went out on the radio circuit, and all the farmers in the area immediately converged on the farm being attacked. After a couple on months of the local defense force taking things into their own hands, since the police seemed incapable, or unwilling to help, things quieted down when these thugs realized that the local farmers were serious about protecting their friends. Quite a few of these murderers were hunted down, and bush justice prevailed.