It’s an airburst, close by, and they’re looking at it, from behind a pane of glass. Probably a state actor, aiming for maximum damage. If they’re not blinded by looking directly at it, they’re about to get glass thrown at their face. Bad scenario for long term survival, they’re likely a goner.

The attention to detail in this comic is pretty great, I like how you can see the blood vessels in his ears in the 3rd panel from the light of the nuclear blast

If I see that, I’m going to run towards the blast.