The only daughter of the late Senator Edward Kennedy, Kara Kennedy Allen, passed away suddenly Friday evening, Kelly O'Donnell of NBC News reports.
The 51-year-old mother of two teens died while at the Sport and Health club, on Wisconsin Avenue in Northwest D.C.
The Kennedy family on Saturday said that her death was caused by an apparent heart attack, which followed her daily workout.
Kennedy Allen had been a survivor of lung cancer and family friends say she had been in remission for a few years.
Kennedy Allen maintained a private life. She made a notably public appearance at the White House August 13, 2009 to accept the Medal of Freedom awarded to her father by President Obama.
Later that month, August 25, 2009, her father Edward lost his battle with brain cancer and Kara was visible during the days of public memorials. She did a reading at the funeral as well.
A longtime resident of Maryland and D.C., she has served on boards for family-related nonprofits and had worked as a television producer years ago.
Kara Kennedy Allen, divorced, is mother to Grace Kennedy Allen who turns 17 Monday, and 15-year-old Max Greathouse Allen.
She is survived by her mother, Joan Kennedy, and younger brothers Edward Kennedy, Jr. and Patrick Kennedy and their families.
The Kennedy family issued a statement Saturday afternoon on her death. It read in part:
"Kara was a warm and caring person. Her children were the light and joy of her life. Her magnificent strength in her successful battle with lung cancer was a quiet inspiration to all us and provided her family and fellow patients with hope. Kara was loved and cherished by the entire Kennedy family."