Why do you think certain people survived looking at it?
Could it be what happens to people who have looked at it and never got the chance to kill themselves after a time and that is the result, or could it be something to do with them being sinners or bad people before this event happened?
We can pretty much surmise that whatever this thing is it's supernatural so maybe this is all God's doing and he's simply separating sinners from non-sinners. Non-sinners kill themselves in what looks like a pain-free state and go to heaven, and the sinners are left behind as punishment (hell) to help seek out the non-sinners left around?