RE: I could not tell what the dude was doing before he shot himself. Was he robbing the store, or just killing himself?
From the article:
... the man shot himself in the head as police were moving in to make an arrest. He had committed the murder just hours earlier, at around 2pm local time in a nearby parking garage
The deceased had just shot and killed a fellow human in a parking garage a few blocks away. The police were looking for him. He saw the police coming towards him, so he went boom.