>> people that knew that this guy was a threat to himself or others, they knew that if he got a traffic stop, he got pulled over, he was either going to kill them or kill himself. >> these details helped deputy rivera see that even though the stop did not go as he hoped, he did everything in his power that night to save a man's life. >> i wish i could have gotten him to stop, get him to put the gun down. you try to do your best to help people. sometimes you can't help everybody. coming up -- >> drop the gun! >> it's open season on police as a gunman shoots to kill. >> i made up my mind i'm most likely going to get shot.