Joe McKnight — Ex-NFL Star Murdered in Road Rage Shooting (PHOTO GALLERY)

Breaking News

2:40 PM PT — Cops say they have detained a man they believe to be the shooter — 54-year-old Ronald Gasser. 

Cops say McKnight did NOT have a gun at the time of the shooting. 

Emergency responders tried to administer CPR but to no avail.

Ex-NFL running back Joe McKnight was murdered in a road rage shooting in New Orleans … law enforcement tells TMZ Sports. 

The incident occurred at 2:43 PM. Family members identified the 28-year-old at the scene. 

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. 

McKnight was a high school phenom — considered the best running back in the country.

He played college ball at USC. He was drafted by the NY Jets in 2010.

Story developing …