Updated: 7:36 p.m. EDT

Big Brown backed up his trainer’s boasts with an explosive finishing kick and won the Kentucky Derby on Saturday, a commanding victory turned somber by the fatal breakdown of the filly Eight Belles on horse racing’s biggest day.

The cheers for the winner’s 4 3/4-length victory were cut short when Eight Belles, the runner-up, collapsed while galloping out near the second turn. She broke her two front ankles and was euthanized on the track minutes later.

“When we passed the wire I stood up. She started galloping funny. I tried to pull her up. That’s when she went down,” said her distraught jockey, Gabriel Saez