ARCADIA (CBSLA) – For the second time in just the past two weeks, another round of tests will be conducted Thursday at Santa Anita Park in Arcadia in the wake of 21 horse deaths that have forced the park to shut down both its racing and training tracks indefinitely.

The 21 horses have died while racing or training at Santa Anita since Dec. 26. The latest horse died Tuesday morning. A 4-year-old filly named Let’s Light the Way suffered a shattered bone in her knee or foot during a workout and was forced to be euthanized.

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The Santa Anita Park racetrack. March 7, 2019. (CBS2)

Hours after that death, the track announced that all racing activities at the park had been suspended through at least this weekend. The training track, however, could reopen as soon as Friday, officials told CBS2.

Experts examine the main track at Santa Anita Park on March 7, 2019. (CBS2)

According to the Los Angeles Times, nine of the deaths have occurred during training on the main dirt track, seven have occurred during racing on the main dirt track, and five have occurred on the turf track. None of the deaths have occurred on the training track.

“The objective here is a uniform surface, a consistent surface, and that’s more of a challenge when you get a whole lot of rain in a short amount of time,” Mike Willman, a Santa Anita Park spokesman, told CBS2 Thursday.

Santa Anita was projected to make about $20 million in Saturday’s canceled races.

“Economic concerns are not a concern,” Willman added. “The safety of our equine athletes, our jockeys, our exercise people, are paramount.”

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This marks the second closure at the park in the past two weeks. Santa Anita temporarily closed the main track for several days last week to have a different expert — Dr. Mick Peterson, director of the University of Kentucky’s Agricultural Equine Programs — do an evaluation following the 19th horse death. The main track was closed to live racing from Feb. 25 through Feb. 28, but reopened to live racing on Friday, March 1.

Since live racing resumed, two more horses, including Let’s Light the Way, have died. A four-year-old filly named Eskenforadrink had to be euthanized after getting injured during a race on Saturday, March 2.

The park’s former track superintendent, Dennis Moore, will be conducting the latest inspection of the racing surface, along with Dr. Peterson. The experts will likely looking at whether the heavy rainfall which has fallen across the region over the past few months has factored into the death toll.

Moore and Peterson will be doing “additional testing of the track to ensure track consistency and uniformity for both training and racing,” Santa Anita said in a news release Thursday.

“The track will be closed for live racing and training until our outside experts confirm the soundness of the track and let us know that it is safe to resume racing,” Tim Ritvo, chief operating officer of track owner The Stronach Group, said in a statement.

Moore was Santa Anita’s track superintendent until he retired in December. He is now track superintendent for Del Mar and Los Alamitos race tracks.

Some animal-advocacy groups, including People for the Ethical Treatment of Animals (PETA), have called for a halt to racing at the track and for investigations into the trainers and veterinary records of the horses that have died.

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(© Copyright 2019 CBS Broadcasting Inc. All Rights Reserved. City News Service contributed to this report.)