Responses

The non-MC characters on the scene got infected by the monster-ification, which has some kind of 'unknown' electromagnetic wave either as a byproduct or the cause. Maybe a form of radiation.
Anyway, MC is immune to it, but everyone else turned monsters... He turned super and probably had a blackout while he was in his alternate form. When he woke up, everyone else had been killed.
What the fuck just happened? Can someone explain to me what was Chapter 3 about??