im trying to do the mission called 'pure blood' but i cant get past the part with the thug, butcher and about 10 normal zombies. now ive gotten out of it before and after i died i was somewhere else and i could continue doing side quests, but i cant remember what i did.

i really need to get away from this mission as its seriously pissing me off

ive got guns, i just dont have any bullets. i think there is a flaw with the game because everytime i die in the mission 'pure blood' all the zombies have all their health back.