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The storied Santa Anita racetrack outside Los Angeles is suspending races at least through the weekend after 21 horses died at the track over the last 10 weeks, a company spokesman confirmed to NBC News.

Officials want to be “very proactive” and do all the testing on the track's surface that needs to be done after heavy rains, Tim Ritvo chief executive of The Stronach Group, which owns Santa Anita told The Associated Press on Tuesday.

Ritvo confirmed to the AP that there would be no weekend races but did not say when racing would resume. The racetrack was scheduled to hold the Santa Anita Handicap on Saturday, a race with a $600,000 purse.

He said in a statement Wednesday that the health and welfare of horses and jockeys are the track's top priority.

"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," Ritvo said.

Dennis Moore, a 46-year veteran track expert, will test Santa Anita's mile-long main track Thursday, the park said in a statement.

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A 4-year-old filly, under the tutelage of the Hall of Fame trainer Ron McAnally, suffered a catastrophic spill during Tuesday morning workouts on the main track, Santa Anita officials said.

Southern California has endured an unusually harsh, rain-filled winter, with 16 inches falling on Arcadia, the home of the track, from Dec. 26 through Tuesday.

McAnally suggested to the racing magazine BloodHorse that the effect of the heavy rains on the track could be a factor in the horse deaths.

"Weather is the cause of all of this. I loved that filly," a visibly shaken McAnally told the magazine shortly after Lets Light the Way, who was owned by McAnally's wife, was euthanized because of a shattered sesamoid bone.

"I bought her at the sale," McAnally said. "I feel as bad as anybody, but that’s the first I had. I wanted to cry when we had to put her down."

While deadly accidents are a constant threat in horse racing, the number of recent fatalities stands out. There were 10 horse deaths at Santa Anita from Dec. 26 to Feb. 25 of 2017-18, eight in 2016-17 in that same period and 14 in 2015-16, according to data from the California Horse Racing Board.

After the first 19 deaths this season, Santa Anita shut down its main racing surface for 2 1/2 days last week to inspect the track for any deformities.

The course was declared fit and racing was off and running again — before two more horses died — the filly on Tuesday and two days prior, another filly, Eskenforadrink, that broke down during a third race Sunday.

Of the 21 that have died since Dec. 26, seven have occurred during a race on the dirt, five during a race on turf, and nine during training on dirt.

Animal-rights activists staged a protest outside Santa Anita on Sunday in response to the mounting death toll.

People for the Ethical Treatment of Animals (PETA), which has helped organized protests outside the track in the wake of the recent spate of horse deaths, released a statement Tuesday saying the suspension of racing is "the right thing to do."