An athlete competing Saturday in the Ironman United States Championship in the Hudson River died after having a medical problem during the swimming portion of the triathlon.

A publicist for the race organizers said the competitor, whose name was not immediately released, “experienced distress” during the 2.4-mile swim at the start of the competition. The swimmer was taken to a hospital but did not survive. The organizers said the cause of death was not yet known.

Contestants in the race, the first Ironman competition in the New York area, followed the swim with a 112-mile bicycle ride through the suburbs and then a 26.2-mile run, which was to end at Manhattan’s Riverside Park.