Bet his last thoughts were...”HEY! It is not supposed to happen this way!” just before the floor came up to hit him.
My thoughts exactly. “Noooooo!”
He probably didn’t expect to get out alive but expected to take a lot more people out first.
Even if the police were exactly the opposite of the ones in Uvalde, and if they were in the parking lot when this started, the shooter would have had time to kill quite a few people before they got him stopped.
The last few seconds of his life were quite a surprise and not at all what he had planned. Thank God.