There was one that happened in Tucson just yesterday.
An off duty Officer driving his own car stopped to help what looked to be a stranded group of folks whose car had died. While talking to then he noticed they were acting kind of suspicious as one kept trying to get in the Officers car. He tried to call for backup on his own radio and the suspect knocked the radio out of his hand, punched the Officer and then pulled a gun on him. They fought and the suspect was able to keep his gun and back away from the Officer who then drew his own weapon and shot the carjacker. Dead carjacker with a history of car theft, assaults and weapon misconduct charges. The other 3 folks were detained at the scene. It turns out the suspects gun was one of those BB guns that looks just like a semi automatic pistol.
