I'm sorry Roy, but technically and reality-wise (while perhaps not emotionally), they do.  Look we ALL want all situations to end quietly and non-violently.

I am NOT saying "don't do what is possible to try and help them, if it can be done without endangering others."  

However, their safety IS forfeit if/when they're putting others' lives in danger. 

They come last in that case, not first.  

If they are shooting at others, threatening someone or holding someone hostage, etc.  By pointing a gun at someone, they have made a choice for themselves.  Not a good one either.

This is not an unknown in today's society.  It's not as if anyone is unaware that "if you become violent, start shooting at people, threaten someone, attack cops, etc." you might get shot and/or killed.

Mentally ill or not, it doesn't then equate to stupid or uninformed.  You start waving a gun around?   ...you ARE starting down the road to forfeiting some or all of your rights, including and up to, your life.