ARCADIA, California (Reuters) - Vino Rosso won the $6 million Breeders' Cup Classic on Saturday at Santa Anita Park in a race that was marred by the death of another horse.

Vino Rosso stormed across the finish line in a rout but Mongolian Groom never made it that far, having been pulled up after suffering an injury to his left hind limb.

The four-year-old gelding was taken from the track in an equine ambulance after being shielded from the crowd of 67,811 by a large green screen.

Favourite McKinzie (5-2) was a distant second and Higher Power (9-1) finished third.

Mongolian Groom (15-1) was in contention early in the 11-horse race on the fast dirt surface but slowed near the top of the final stretch.

Jockey Abel Cedillo pulled him up and veterinarians rushed to attend to the stricken horse.

"Mongolian Groom sustained an injury in the Breeders' Cup Classic today and was immediately attended to by an expert team of veterinarians," Breeders' Cup spokesperson Jim Gluckson said in a statement.

Gluckson said the veterinarians could not repair the damage and recommended a "humane euthanasia."

Gluckson said an independent evaluation into what caused Mongolian Groom to break down would be launched and the results would be made public when it is complete.

"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."

No horses were injured through the first 11 Breeders' Cup races on Friday and Saturday although several were scratched by veterinarians prior to their starts.

Santa Anita Park has been under intense scrutiny following the spate of horse deaths at the famed Southern California track since late December. The death of Mongolian Groom raised the toll to 37.

The race track implemented a series of reforms around drug use and brought in a record number of veterinarians prior to the start of the event.

Animal rights activists protested outside the venue on both days, saying the sport is tantamount to animal cruelty and calling for it to be banned.

Horse safety officials this week said the track was the safest in the United States.

Opponents of the sport responded to the latest death of a racehorse with outrage.

"Ignore everything else you've heard and read about 'safety' and horseracing," said Patrick Battuello of activist group Horseracing Wrongs.

"If they can't prevent a kill at this track, on this day - with the whole world watching and vigilance at an all-time high - they can't prevent, at least not in any meaningful way, kills period."

"It's inherent to what they do. And it must end. Now."

Mongolian Groom was trained by Enebish Ganbat and owned by Mongolian Stable, which is best known for producing 2015 Breeders' Cup Turf Sprint winner Mongolian Saturday.

The death overshadowed Vino Rosso's impressive win, which was the first in the Classic for trainer Todd Pletcher and jockey Irad Ortiz.

Pletcher has won 11 Breeders' Cup races in total and Ortiz, who picked up four victories this weekend, has notched a total of nine wins at the world championships, which attracts horses from around the world.

Pletcher acknowledged that tensions were running high in the horse racing community as this year's Breeders' Cup approached.

"It's something that we were all very concerned about coming in. We were anxious not only about running in huge races like these, but also hoping that everything would go smoothly and safely.

"Everyone took every precautionary measure they possibly could."