The 35-year-old was in a Ferrari which collided with a BMW in the Pacific Palisades area at 18.31 on Tuesday (02:31 GMT, Wednesday).
Gibello's passenger was pro golfer Bill Haas, who was in town for the Genesis Open.
A Los Angeles Fire Department report said the Ferrari driver was pronounced dead at the scene after the vehicle reportedly rolled over.
A third vehicle was also involved when the Ferrari clipped a Toyota FJ SUV just before the crash.
Details of the crash were updated on their website.
Wilson, 46, wasn't seriously injured in the crash, KTLA reported. Haas was taken to a hospital but released with no serious injuries. According to Fischer, that vehicle was being driven by actor Luke Wilson.
The PGA Tour and Haas' management company, Players Group Management, released a statement that Haas has left hospital and is heading home to SC.
The statement added: "his deepest condolences go out to the host family during this tragic and hard time".
The junior golf tournament, one of the most prestigious on the AJGA, was named for the Haas family a year ago and is held every June at Sedgefield Country Club.
"Bill was very fortunate", Haas told Golf Channel. He began the week No. 67 in the official World Golf Ranking.
Haas is the son of Belleville native Jay Haas.