Two horses died Saturday during early Preakness Day races at Pimlico Race Course in Baltimore, Maryland.

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In the opening race of the day, 9-year-old Homeboykris won the race by a half-length. After having his picture taken in the winner's circle, he collapsed and died. Track officials believe the 9-year-old gelding suffered cardiovascular collapse.

"So apparently, not long after leaving the winner's circle, the boy that takes care of him said they had gone probably 100 yards, and he got wobbly and fell over and he pretty much was dead when he hit the ground," said Francis Campitelli, Homeboykris' trainer. "They're thinking at this point it was some sort of heart attack -- you know, ruptured aorta or something like that. We won't know until they do a necropsy on him, just to find out exactly what happened."

Homeboykris won the Champagne Stakes in 2009 and finished 16th in the Kentucky Derby in 2010. He had just won his 14th race in 63 career starts.

The horse will be taken to New Bolton Center in Pennsylvania for an autopsy.

"The horse was in really good health for a 9-year-old horse," Campitelli said. "When we claimed him, I was really amazed at how good of health (he had). He had no infirmities in his legs. He was just in such good health, you know? The horsey was a champion. I mean, he went out a winner. He was a brave horse at his age. And this was a very tough race that he was in today. He ran a great race. We're all proud of him."

Later in the day, Pramedya fell while racing around a turn in the fourth race.

Racing officials said the 4-year-old filly was euthanized on the track after breaking her left front cannon bone. It was only her fifth career start.

Jockey Daniel Centeno was thrown off the horse onto to the turf. Centeno broke his right collarbone. He was transported to Sinai Hospital by ambulance, the Baltimore Sun reported.