>> the gunman fires a sickle shot striking sergeant kellermann in the face. >> i was still trying tohim. you know, hey, buddy, put the gun down. trying to get him to put the gun down. trying to get some time of demeanor with him. i don't remember the gun blast. i remember hearing it, and i knew it was him that shot, and i felt the percussion on my face. >> just as i was about to fire my first shot he shot, and it kind of distracted me for a second. >> shortly after he shot i fired my first shot, and you see the window on the car that he's leaning on blow out. that was my first shot. >> in an instant, several officers open fire on the gunman, as officer tyson riley races to the aid of sergeant kellermann. >> the other officers that were there, i trust them with my life. i knew that they were going do anything they could to protect me and sergeant kellermann, and at that point i chose to holster my weapon and go to him. >> hill goes down. he is fatally wounded. >> stay down! stay down! stay down! >> officer raleigh tends to his fallen colleague out of the camera's view, but the dramati