The death of Robert Kennedy's granddaughter at age 22 is the latest in a long list of tragedies stretching back to the 1940s to have struck America's most famous political dynasty.
Saoirse Kennedy Hill was found unresponsive at the Democratic family's sprawling compound at Hyannis Port on the Cape Cod peninsula in Massachusetts on Thursday, according to multiple US media reports.
Her cause of death wasn't immediately confirmed but The New York Times said she had died from an apparent drug overdose. Kennedy Hill had written about her struggles with depression.
"Our hearts are shattered by the loss of our beloved Saoirse," the Kennedy family said in a statement to AFP. "She lit up our lives with her love, her peals of laughter and her generous spirit."
"The world is a little less beautiful today," said 91-year-old Ethel Kennedy, Saoirse's grandmother and widow of Robert Kennedy who was assassinated in 1968 while on the campaign trail.
Saoirse was the daughter of Courtney Kennedy Hill, one of 11 children that Ethel and Robert, younger brother of former president John F. Kennedy, had together.
One of the first police responders answering an emergency call at the Kennedy property radioed that the victim was in cardiac arrest when he arrived, according to the local daily Hyannis News.
An autopsy revealed no trauma inconsistent with lifesaving measures, the paper added.
The Kennedys, often considered the closest thing the United States has to a royal family, have been plagued by tragic and untimely deaths for decades.
Edward Kennedy, John and Robert's brother, once even talked about whether there was a "curse" hanging over the family. Commentators and US media regularly refer to the "Kennedy curse."
Four of patriarch Joseph Kennedy's nine children died violently.
The most famous of them -- John -- was assassinated on November 22, 1963 during a visit to Dallas, Texas when he was president and just 46 years old.
Lee Harvey Oswald was arrested and charged with Kennedy's death but was himself shot dead by Jack Ruby before he could be put on trial.
Numerous conspiracy theories surround the assassination despite an official commission ruling in the year after Kennedy's death that Oswald had acted alone.
- Plane crashes -
By the time of John's death, the Kennedys had already been struck by tragedy.
The eldest son of Joseph and Rose Kennedy, Joseph Jr, was killed in action in August 1944 while serving as a bomber pilot during World War II.
Then in 1948, their second eldest daughter Kathleen died in a plane crash in the south of France aged just 28.
Robert "Bobby" Kennedy, who was US attorney general during JFK's presidency, died in Los Angeles on June 6, 1968 as he campaigned to become the Democratic nominee for that year's presidential election.
Kennedy, the leading candidate for the nomination, was shot and mortally wounded by 24-year-old Palestinian Sirhan Sirhan as he walked through a crowded hotel kitchen after winning the key California primary.
Sirhan, who is still serving a life sentence for the murder, said he killed 42-year-old Kennedy because of his support for Israel.
Later generations of Kennedys have also suffered immense tragedy.
In 1998, John F Kennedy's son John Jr died in a plane crash at the age of 38. His wife and sister-in-law also died.
Two of Robert Kennedy's sons also suffered untimely deaths: David, from a drug overdose in 1984 at age 28, and Michael, in a skiing accident in 1997 when he was 39.