Just what was going on in Lanza's mind at the time?

There is so much unknown yet, there is no way to speculate.
One thought that has occurred to me was if he may have intended to only harm adults, but upon realizing the psychological trauma he’d inflicted on the kids, he might have thought that they were better off dead, and then turned on the kids and took his own life. We will probably never know.

@hearkat makes sense.

…although now they’re saying that the mother’s body was found at the home, not at school… so then I don’t see why he’d go to the school then. I was guessing that his mother was the prime target.

Kip Kinkles parents were teachers, and wasn’t one of the Columbine killers a teachers kid? I wonder if it has to do with jealousy. Mom not having enough time with him because she is so focused on other people’s kids.

I think one of the many things must’ve been jealousy as @Judi mentioned. Scares me to think of what else was going on up there.

@Judi – that thought had just occurred to me and you beat me to making the comment.

There are also reports that he had a personality disorder or autism… and the guns were legally owned by his mother.

He had Asperger’s syndrome and either he or his brother played a violent video game as posted on Facebook by one of them. I think we’ll know more later today (Saturday) what was going on in his mind. He could have been on pharmaceuticals, too.