Damien

He apparently kept shooting until he ran out of ammo then sat there waiting for the police.

I know it's a pointless question we always ask and the answer is that their minds don't work the same way but how can someone do that? He's killed someone's child/brother/sister and maybe their mother/wife and/or father/husband. So many people's lives ruined for nothing.

I saw a video of the aftermath on Twitter. Awful screams of people dealing with the dead/injured.