I would have to think it was personal. I also think that, as seems to me often to be the case, he was shocked and sickened by his own actions, and put an early end to his planned mayhem.
I think this was the case at Columbine. Even though they did kill a number of people, they were in a position to kill multiple times that many, except that the whole thing was going sour for them.
Even the Newtown shooter quit after a point, although it seems he did keep at it for a long time, an indication of the depth of his psychosis, as I see it.
The joker guy was similar, truly nuts.
A typical black criminal would not commit suicide. They would try to escape and survive. A muslim would commit suicide, but only at the last resort before getting caught, trying to do as much damage as possible. This was acting like a white school shooter.