Currently, a significant fraction of random NPCs will be aggressive, but not immediately hostile, telling you to get out of their territory before they kill you. The problem is, they seem to invariably turn hostile and start attacking around ten turns later, which is nowhere near enough time to make it to a safe distance even if you just leave your weapon where you dropped it. If the NPC is armed with any kind of gun, I have yet to find a way to survive one of these encounters without being similarly armed. They even seem to know exactly where you are without having line of sight. I lost my last character after I managed to lose such an NPC in the woods nearby, only to have him show up a few minutes later in a farm in the opposite direction to the one I lost him in. He then proceeded to shoot me despite the fact that there were no fewer than six zombies of various kinds between me and him.
It would be nice if the NPCs at least gave you enough time to leave their visual radius before they turned hostile, so they don’t represent immediate death to a new character.