Normally if you were in the right you have nothing to worry about, at least from the Police. Now if you just plugged 3 members of the messican mafia, the possible retribution from them might induce you to keep your mouth shut..
There was a case in Phoenix where a guy shot 2 bad ass bouncers who he had a road rage altercation with, they followed him into a parking lot, he shot annd killed both and took off. The only details they had on him was that he had a Honda of some kind. If he went to the poliice right away he could have pleaded self defence, sounded like it to me. Took the police 3 years, but they tracked him down eventually by interviewing every owner that sold a Honda, and he went to jail.