A witness told NOLA.com ... she saw McKnight trying to apologize to another man after some sort of traffic incident.
The witness says the man then pulled out a gun and shot McKnight -- and while standing over him screamed, "I told you not to f*** with me" ... then fired another shot into his body.
Or maybe the guy was just a hair trigger road rage nut.
I wonder why he waited for police? Better than fleeing after losing it, I guess.