What Happened?

I found this pic from deviantart, a amazing concept that is clear to anyone looking, love it.

And this is the description from his author:

Before turning in the keys to my old apartment, I spent a little time shooting in the empty space. I didn't have any lighting with me, and I didn't have a lot of time, but I did get a few shots.
A bit more morbid than most of my stuff, but I overheard someone using the phase, "curiosity killed the cat" recently, and couldn't get the idea out of my head.

What indeed happened with the five blackzentai suit men and the one animal?