A 34-year-old Nebraska woman has died after she was hit on a bicycle while taking part in the Ironman Boulder race.

Michelle Walters of McCook, Nebraska, was hit by a vehicle while riding on a major highway north of Boulder on Sunday, the Colorado State Patrol said.

Ironman event coordinators issued a statement confirming the woman's death. "We are deeply saddened to confirm the death of one of our athletes at IRONMAN Boulder," organizers said.

The driver and details of the accident have not been released. Alcohol and speed are not believed to be factors in the crash.

Participants began with a 2.4-mile, one-loop swim in Boulder Reservoir. Athletes then continued on a challenging 112-mile, multiloop bike course, followed by a 26.2-mile running course.

Last year, a 40-year-old Virginia man died three days after completing the Ironman triathlon in Boulder. Brian Godlove, of Fairfax, died in a Boulder hospital after racing on Aug. 2.

Ironman Boulder results show Godlove completed the 2.4-mile swim and 112-mile cycling portions of the race, but he did not do the final 26.2-mile running leg.

Godlove died of complications from dehydration and rhabdomyolysis associated with excessive exercise, Boulder County Coroner Emma Hall said. Rhabdomyolysis occurs when muscle tissue rapidly breaks down and enters the bloodstream, and it can be brought about by extreme exercise.