LOUISVILLE, Ky. -- Boy, did Eight Belles hang with the boys.

All that heart and her gallant fight, however, ended in the worst of all possible ways: a breakdown, an ambulance on the track. And, with no other choice, she was euthanized by injection.

The day began with hope and pomp. Bolstered by the sentimental support from 157,770 fans and endorsed by presidential contender Hillary Clinton and cheered by daughter Chelsea, the filly finished second in the Kentucky Derby on Saturday.

She crossed the wire 4 3/4 lengths behind favorite Big Brown. Then, with the second-largest crowd in Derby history still whooping it up, Eight Belles collapsed with two broken front ankles.

The magnitude of what happened was slow to reach the fans at Churchill Downs. Not only was a horse down, but it was the filly. And horse racing -- with the memory of Barbaro still fresh and the death of a horse coming only a day earlier on Kentucky Oaks Day -- had to confront grief one more time.

"There was no way to save her. She couldn't stand," trainer Larry Jones said. "She ran an incredible race. She ran the race of her life."

Jones' voice broke and tears glistened in his eyes as he considered his barn without Eight Belles' head poking out of her stall.

"Losing animals like this isn't fun. It's not supposed to happen," he said. "We're heartbroke. We're going to miss her, no doubt."

The field of 19 colts and the dark gray filly were galloping out around the first turn when Eight Belles suddenly went down on both front legs and jockey Gabriel Saez slid off.

"When we passed the wire I stood up," said a distraught Saez, a first-time Derby rider. "She started galloping funny. I tried to pull her up. That's when she went down."

Filly Eight Belles broke both front ankles after the wire in the Kentucky Derby. She was euthanized on the track while Big Brown's victory was celebrated. AP Photo/Brian Bohannon

An equine ambulance reached her near the second turn.

Eight Belles appeared to be galloping out normally around the first turn and was headed into the start of the backstretch when she dropped without warning. The crowd was busy high-fiving and celebrating and the distance from the grandstand prevented many from realizing what had happened.

"Everyone breathed a big sigh of relief that everyone came around the track cleanly and then all of a sudden it happened," said Dr. Larry Bramlage, on-call veterinarian.

Quickly, word spread about the horse that was down in the second turn. Fans focused binoculars on the scene, using Saez's red helmet to identify the horse.

"That's one of the saddest things I've ever seen," said fan Kathleen Brower of Louisville. "We went from the high for the winner and something like this happens. It just takes the wind out of the sails."

No more so than for Jones and owner Rick Porter.

Eight Belles could have easily been the wagering favorite in Friday's Kentucky Oaks, an all-girl showcase. But Jones and Porter decided to run her against the boys despite the fact that she had never done so before. She had, after all, solid credentials with a four-race winning streak.

Jones won the Oaks with Proud Spell and set himself up to pull off the double.

At first, Jones didn't realize anything was wrong until he began walking back to the stable area and saw Saez aboard another horse.

Reached by cell phone, a somber Porter said simply, "It's not a good time."

Afterward, Jones disputed any suggestion that Eight Belles had no business taking on the boys.

"It wasn't that, it wasn't the distance, it wasn't a big bumping match for her, she never got touched," he said. "She passed all those questions ... with flying colors. The race was over, all we had to do was pull up, come back and be happy. It just didn't happen."

If Eight Belles had labored to the finish line and been falling farther behind Big Brown in the closing strides, then Jones said he would have "really second-guessed ourselves severely and kicked ourselves in the pants."

But she hit the wire strongly and galloped around the turn without a hitch, leaving the trainer in the white cowboy hat feeling proud. Jones also trained last year's runner-up, Hard Spun.

"We were ecstatic," he said.

For a time, anyway.

Part of Eight Belles' appeal was her status as the first filly since 1999 to run in the Derby; the last to win was Winning Colors in 1988.

Hillary Clinton didn't attend the race, but she ordered her daughter to bet the filly. Eight Belles, who went off at 13-1, repaid the fans' faith by returning $10.60 and $6.40.

Winning jockey Kent Desormeaux and Big Brown galloped by Eight Belles in her waning moments.

"This horse showed you his heart and Eight Belles showed you her life for our enjoyment today," he said. "I'm deeply sympathetic to that team for their loss."

Bramlage said the fracture in Eight Belles' left front ankle opened the skin, allowing contamination to set in. At least one of her sesamoid bones was broken, too.

"She didn't have a front leg to stand on to be splinted and hauled off in the ambulance, so she was immediately euthanized," he said. "In my years in racing, I have never seen this happen at the end of the race or during the race."

Bramlage was hard-pressed to make sense of yet another breakdown that reminded fans of Barbaro's horrific injury two years ago in the Preakness.

"The difficult thing to explain with her is it's so far after the wire, and she was easing down like you'd like to see a horse slow down by that point," he said. "I don't have an explanation for it."