A woman who was taken to St. Luke's-Roosevelt Hospital after experiencing difficulty during the swimming portion of Sunday's New York City Triathlon has died.

Race director Bill Burke confirmed that the Elmhurst, Ill. Woman died Monday morning. She was believed to have gone into cardiac arrest twice after Sunday's swim.

Her name wasn't released at the request of her family.

Her death comes just one day after a 64-year-old participant passed away after having a heart attack. Identified as Michael Kudryk of Freehold, N.J., he too experienced difficulty during the swimming portion and was spotted unconscious in the Hudson River about halfway into the 1,500 meter swim.

Police said that 26 other participants required assistance for minor injuries or pains throughout the swim, raising concerns about the safety of the event.

One of this year's participants, Namgyal Galden, 27, from Boston, told the New York Times choppy water had made the swim difficult this year.

A study last year into sudden death during triathlons, which was published in the Journal of the American Medical Association, found 14 people had died during triathlons between 2006 and 2008, 13 of whom passed away during the swim. Their research suggested that the swimming part of the race is the most dangerous because open waters hamper rescue efforts to reach struggling athletes.

The Nautica New York City Triathlon, which began eleven years ago, sees participants swim nearly a mile, bike 25 miles, and run 6 miles.

Participants attend a mandatory briefing before the race that includes information about training and staying hydrated. Race director Bill Burke said weather conditions on Sunday were optimal, with relatively mild temperatures and good cloud cover for much of the day.