Four horses have died already this year -- three in the past three days -- at Santa Anita Park.
CNN  — 

The third horse in three days – the fourth this month – was put to death at Santa Anita Park in California Sunday, according to a state horse racing board spokesman.

The 3-year-old horse, named Tikkun Olam, “was involved in a head-on collision with another horse while training Sunday morning” and “suffered catastrophic injuries, necessitating euthanasia,” California Horse Racing Board spokesman Mike Marten told CNN in an email.

On Friday, a 6-year-old horse named Harliss was euthanized after fracturing its right front ankle, and on Saturday 5-year-old Uncontainable was put to death for the same reason.

Golden Birthday, a 4-year-old horse was the first to die this year at the track in Arcadia, northeast of Los Angeles, after being injured during a January 1 race.

The number of horse deaths at the track – almost 40 in just over a year – led officials to briefly halt racing there last year. Santa Anita has since made changes in an effort to increase safety for the horses, including restricting steroids, anti-inflammatory drugs and race-day medications.

Animal-rights organization PETA on Sunday called on the state’s horse racing board to suspend racing.

“Three dead horses in three days requires immediate action,” PETA said in a statement. “If it takes the closure of a track to stop the deaths, then close the track.”

Santa Anita Park said in a statement this weekend that horses raced or trained at the park “more than 420,000 times over the last year with a 99.991% safety rate.”

The park houses 2,000 horses and is one of the largest equine training facilities in the country, according to its website.

CNN’s Stephanie Becker and Alaa Elasser contributed to this report.