I recently ran into an acquaintance who showed me serious gashes on his hand. I asked, "what happened?", and he proceeds to tell me how he almost got carjacked. It was 2PM, a nice day, very busy area in a moderate sized city in MA. He had pulled over and gotten out of his car, and was leaning against car talking on cell phone. He's approached by two young guys, who say "we want your car". He kinda laughs, but then they start ominously moving in. He catches the first guy with a hard karate chop right to the adams apple. He said that guy went down like a rock. Then the fight is on with the second guy. He said he pummeled the second perp, and in the process he severely cut his hand on the perp's oversized jewelry!
So now the fight is basically over. My guy has beaten back the threat, but is bleeding badly. All of a sudden, my guy hears a voice behind him. He turns and this new person says, "it's OK, you're good. I'm a cop. I saw the whole thing. You get to the hospital to get that taken care of and I'll take care of this mess." My guy couldn't believe his luck, that he had a LEO as a full-on eyewitness. He took off and went to hospital.
After my guy gets out of hospital, he goes to local police station to follow up on the LEO's report about the attempted carjacking. The officer behind the desk says, "what attempted carjacking? We've got no reports of that incident". At that point, my guy realizes how lucky he probably was, as the "LEO" was almost assuredly an accomplice to the perps. My guy said he never realized that third guy was behind him. Could have ended very badly for my guy.