Go the back way get the herb, hop in the back window of the first house, and collect the bullets/grenade. Hope back out the window, wax the first bitch zombie(semi-zombie?).

By this time, the towns a flutter. Keep on going around the back way, come around the corner, wax the dude. It takes like 3 or 4 deaths before another cutscene and they ramp up the zombie attack. I have also noticed if you don't go too deep into the village towards the exit, the chainsaw dudes don't attack. At this point, its a matter of run far away, turn around, try to kill some more, repeat. Remember you have a grenade, so when they are bunched up dont hestitate to throw it.

Remember leg shots make them fall to the ground, the heads maximum damage, and you kinda want to run around in circles hoping someone separates from the pack so you can wax em.

Only run in the house if shit is hitting the fan and you can't survive outside, move the chest to barricade the window, grab the shotgun and try to make your last stand on the top(kick out the ladder, shotgun people outside of the windows...hell, jump out the window and run far away again)