Zombie Apocolypse

It had been 3 weeks since the start of the apocalypse. You were doing your weekly shop when the sirens came, police sirens rang across the town ensuring everybody was safe in their homes. Since then, you haven’t left the shop you were in. Everything is silent in there, the windows are boarded up and the only people are you and the shopkeeper Erin. Occasionally, you will see a creature stumbling across the street, but you have never seen a horde, not while the store was quiet. That was, until, you spotted somebody in the distance, his skin was coloured normally and he didn’t have any visible wounds, he was screaming and sprinting towards the store. You and Erin hid behind a shelf, because the most dangerous things in an apocalypse are the people who went insane. Eventually, he reaches the front of the store, still screaming and shouting for you to let him in, that was when you saw multiple creatures, zombies flooding across the street, slowly stumbling towards the supermarket being attracted by the noise. A horde was coming. There are only a few ways to be infected, if you are bitten by a zombie but still escape with your life, you will come back as a zombie. The zombies aren’t intelligent enough to purposely infect you, they want to rip you apart and eat you, so if you are bitten but survive, you will turn into a zombie within 3 days. The other way you can be infected is by stumbling across any biohazard zone and being in there too long, when a zombie dies, their blood, scent and saliva all carry the infection, so when a horde of zombies die in one place, staying in the dead zone too long will cause a human to be infected.