It has been reported by several local news outlets that a sheriff's deputy was shot but no civilians were injured in the incident. Sheriffs then tased the suspect and opened fire when that did not stop him.
The department says the man was taken to Scripps Memorial Hospital La Jolla.
A video posted to social media appeared to show a deputy firing four shots at a man who collapsed in front of a ticket window as bystanders exclaimed.
The concert, for which tickets were sold out, was scheduled to follow a full slate of horse races at the track, the station reported.
The race track later tweeted that the situation was contained, and the concert would go on as scheduled.
The San Diego Sheriff's department confirmed to Fox 5 that one person was injured in the shooting.
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No other details were immediately available, and police are yet to release any information on the incident.
Ice Cube responded Monday to a fan who tweeted about the shooting that took place at the Del Mar Fairgrounds last night. TVG documented the shooting while calling a race with a broadcaster repeatedly saying: "There is gunfire at the track".
As is our special events protocol, substantial law enforcement and private security was on site in anticipation of the event.
We also are thankful for the work and training our personnel have done with the Sherriff's Department regarding possible active shooter incidents.
Following the shooting, the concert moved "forward as planned", the racetrack said.
We will continue to fully cooperate with the Sherriff's Department in their investigation and will refer all questions concerning the incident to them.