My Sister!!

This is a short story I made about three years age, and I forgotten about it until now.
Two highschool girls escape from their over-run campus full of moving corpses, with makeshift weapons.
One of the girls in her gym uniform, spots a person on top of a car, that is suroned by moving corpses.

When the teen girls got a closer look they saw it was the girl in a gym uniform, younger sister whose in middle school.