Apart from the instant, wincing, reaction - the police could have shot for his legs and brought him down so that he was harmless - unpleasant, but he would have his life before him.
Personal experience; I was crossing the playground to the gym block, accompanying a class of girls (aged 10/11)ready to get changed after break when I was confronted by one of our pupils (14) pointing a 'gun' at me. (He was in isolation because of bad behaviour and so took his break when others were back in class.) I knew this boy, that his brother was often drugged-up, that he had been caught with small quantities of cannabis and that his family dealt in a big way. (Yes we told the police and eventually they got them.) I also knew that, although small, the gun could have been the local dealers' weapon of choice (.22). I did not know that it proved, later, to have been a toy. I wanted, more than anything, someone to render this kid harmless whilst I shooed the class away and joined them in the safety of the gym.
America does, of course have a lot of issues because guns are so readily available. Perhaps their police should have non-lethal deterrents available. I offer this for what it is worth.