SCP Foundation

There was a containment breach at one of the facilities where SCP-008, "the Zombie Virus," was contained. It was caused by the Chaos Insurgency, but the Zombie Virus was also enhanced with SCP-914, called "the Enhancer Machine." As a result, the virus mutated and infected some insurgents, but did not immediately turn them into zombies. It also acquired the ability to infect other anomalies.

Write how you want your story to begin, or if you don't want to start your own, then I'll leave you with one.

You're a Class D prisoner in one of many locations, but you don't know which one. It's a seemingly quiet day; luckily, you haven't died yet. But that afternoon, you hear an alarm and the cell doors open. You look outside, but all you see are the alarm lights. In the distance, you hear gunshots and some screams, but you also hear something else that's hard to make out because of the chaos, but it sounds like growling.