Apparently from what I've gathered. The guy who was shot in the head was attacking the Kenosha Kid, and throwing things at him. He ran up on him and I guess that's when he got shot.

Edit: Yeah, in the video of this post. You see red shirt guy running up on rifle guy. Rifle guy turns right as red shirt guy is on him, that's when he gets shot. Rifle guy (green shirt, hat, blue gloves) is on the phone afterward, saying he thinks he just killed someone. He then takes off, presumably seeing the mob beginning to approach.

Not sure why red shirt guy was attacking him though.

Apparently from what I've gathered. The guy who was shot in the head was attacking the Kenosha Kid, and throwing things at him. He ran up on him and I guess that's when he got shot.