(SANTA ANITA, Calif.) — Heading into its 2019 finale, California’s famed Santa Anita racetrack had endured a harrowing season in which 36 race horses had been ridden to their deaths since last Dec. 26. With massive safety precautions in place, officials were optimistic that the season would end on a high note with the Breeders’ Cup championship on Saturday. It was not meant to be.Mongolian Groom, a 4-year-old thoroughbred, suffered a “serious fracture” to his left hind limb just seconds from the finish line in the final, main event of the Breeders’ Cup, and was subsequently euthanized Saturday night, officials said.A national TV audience watched pre-race favorite McKinzie and challengers Vino Rosso and Mongolian Groom exit the track’s final turn in the $6 Breeders’ Cup Classic, when suddenly Mongolian Groom pulled up, leaving Vino Rosso to outduel McKinzie down the stretch for the upset win.As Vino Rosso’s trainer Todd Pletcher and jockey Irad Ortiz Jr. celebrated the 4-year-old colt’s victory, officials rushed a green screen onto the track to block the view of onlookers as Mongolian Groom was loaded onto an equine ambulance.”Mongolian Groom … was immediately attended to by an expert team of veterinarians led by Dr. Ryan Carpenter,” Breeders’ Cup officials said in a statement following the race. “During their evaluation at the equine hospital at Santa Anita, they observed a serious fracture to his left hind limb. … Given the extent of the injury, Dr. Carpenter, in consultation with (three colleagues) recommended humane euthanasia of Mongolian Groom.”The death was the third at the track in the last nine days, following the euthanizing of 2-year-old filly Bye Bye Beautiful last Sunday and 5-year-old mare G Q Covergirl two days before that.Saturday’s two-day Breeders’ Cup event, considered the Super Bowl of horse racing, was under intense scrutiny amid increased calls for horse safety. As animal rights protesters marched in front of the track’s main entrance, officials were said to be taking every precaution, even scratching horses with only minor injuries, in order to run a clean event.Over the summer, California Governor Gavin Newsom had called for Santa Anita Park to be shut down until experts could determine why so many horses — 29 at that point — had died since the start of the season. The track responded by enacting a series of changes to its racing procedures — including a “zero tolerance” policy for the use of almost all medication on race day and additional restrictions on the use of whips — and racing continued.Before Saturday’s final race, the weekend’s other 13 Breeders’ Cup races ran without injury. But the final race was marred by tragedy.For horse racing fans, the sight of a horse breaking down on national television was reminiscent of 2006, when Kentucky Derby-winner Barbaro broke his leg in the Preakness and was eventually euthanized. Thirty-one years before that, in perhaps the most famous race horse death of all, the undefeated filly Ruffian broke her leg in a nationally-televised match race against Kentucky Derby winner Foolish Pleasure, and was euthanized after an attempted surgery.Following Saturday’s announcement that Mongolian Groom had been euthanized, Breeders’ Cup officials said they would conduct an investigation into the matter.”Breeders’ Cup has engaged world-renowned veterinarian Dr. Larry Bramlage to conduct an independent evaluation, the results of which will be published when completed,” they said in a statement. “We are committed to working with our partners in the industry to continue to advance safety reforms, with the well-being of our athletes in mind.”Members of the horse racing community said the sport deserved their support.”There’s 77,000 jobs up and down the state of California that are tied in to horse racing,” horse trainer Doug O’Neill told Los Angeles ABC station KABC. “From the guy ripping the tickets, to the shoers putting on shoes, to the veterinarians. There’s so many people tied in to this great sport.”Copyright © 2019, ABC Audio. All rights reserved.