So this random girl was experimenting and whatever she was making got onto her and turned her skin grey, kinda making her zombie-like. She went after anyone who was nearby and made them like her by killing them. It spread quickly. I was a survivor along with countless others. Some of which were from my school.  Most of us got onto a bus, which was my own school bus for some reason and just got almost everyone into the huge bus. After trying to hold the door shut, I woke up.