Netflix series ask Black summer?

Why is this party bunker full of zombies just because the power turn off?

The one guy got a knife in the neck before and immediately attacked someone! Everyone runs away in panic, but they do not know exactly where to go without light. The two infected are on the go and get more and more on their side! So that's how I explain it to myself.

Ok, I also just saw xd was just funny distributed the scenes