Horse Racing has been suspended “indefinitely” at Santa Anita Racetrack in Arcadia, California after the 21st horse death in the past few months. The Southern California racetrack announced Tuesday that the death of a 4-year-old filly who suffered a catostrophic leg injury early that morning was the reason behind the closure.

Races have been suspended through the weekend, and there is no timetable on when they will resume.

The track was scheduled for a major day of racing on Saturday, including the $600,000 Santa Anita Handicap for older horses and the $500,000 San Felipe Stakes for 3-year-old Kentucky Derby hopefuls.

Seven deaths have occurred during races on the dirt track at Santa Anita since the winter season began on Dec. 26. Five have occurred on the turf course, and nine came during training on dirt.

Last week, Santa Anita was closed for two days while the dirt surface underwent extensive testing and was declared fit for racing.

Track officials announced in a statement on Tuesday that a former track superintendent is returning immediately to Santa Anita as a consultant on site as “a precautionary measure with regard to the condition of the one-mile main track.”

In 2014, Dennis Moore oversaw a major renovation of the dirt surface using sand that was dug up in the coastal suburb of El Segundo for construction projects at Los Angeles International Airport. The sand was screened for foreign materials and large rocks.

At the time, track officials said the reddish-brown sand would ensure balanced drainage during periods of wet weather and a consistent, safe cushion for horses year-round. That’s important at Santa Anita, which added several additional weeks of racing to its schedule after the closure of Hollywood Park in Inglewood, California, in December 2013.

It is believed that the heavy rainstorms that have soaked Southern California have played a part in the high number of deaths this racing season.

Santa Anita is set to host the Breeders’ Cup world championships for a record 10th time this fall.