While there were no confirmed reports of additional injuries at the time of publication, TVG confirmed that all of its personnel were safe and accounted for.
Sheriffs then tasered the suspect and opened fire when tasering couldn't contain him.
The sheriff's department said the alleged gunman shot by deputies was taken to Scripps Memorial Hospital La Jolla.
The shooting happened close to an area within the race track where rapper Ice Cube is scheduled to perform a sold out show later on Sunday night.
Shocking footage caught the moment commentators screamed "there's gun fire at the track" and a jockey was flung from his horse. After an argument ensued, Elizarraras pulled out a silver plated semi-automatic handgun and reportedly fired three shots in the air.
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Sheriff's deputies received reports of gunfire at the fairgrounds at around 7 p.m.
No further details were immediately available.
In addition to the Ice Cube concert, the venue's schedule included a full day of races. Broadcasters calling the race live reportedly began shouting, "There's gunfire at the track, there's gunfire at the track", before cutting out the audio, The Blast reports. Just half an hour after the shooting, and with the day's racing finished, the racecourse tweeted that the gangsta rap gig would go ahead as planned.
The racetrack tweeted less than an hour later that the situation has been contained and the concert was moving forward.