To join up with a group giving aid to people. He brought a first aid kit which he did end up using, he helped put out a fire or two (dumpster fire, he wasn’t a heroic firefighter, just some kid), and he used his gun after Joseph Rosenbaum jumped out from behind a car to take it from him, again after being attacked by Anthony Huber, and again after Gaige Grosskreutz pointed his gun at him. The trial is publicly available.
I can confirm the first aid part. I watched raw footage. He shot three people, actually, but they were all in reaction to 1) an individual chasing after him despite his attempting to run away, 2) an individual slamming a skateboard onto his head after the individual chased him down while he ran, 3) an individual who had pulled a firearm from their pants and attempted to fire a shot at him