No one knows anything of the state of the person. I’m sure every single murderer is mentally ill and it doesn’t mean they deserve sympathy. It could have been a very, very dangerous situation with thousands injured.
If he killed a family member or a loved one then I’d be asking them to shoot again just to be sure. I don’t care if they’re mentally ill or not, if you’re violent, attempting to murder someone and then resisting arrest including threatening and bringing an officer to ground then I hope they clock the idiot.