A nine-year-old boy hanged himself on a rope swing in a freak accident at his home, his uncle said.
Jamie Bray was unconscious when his mother found him in the garden of the house in Bishops Waltham, Hampshire.
She desperately tried to resuscitate him until paramedics arrived, but he could not be revived.
His uncle Chris Wheal said it was "every parent's worst nightmare".
"He was playing on a rope swing in the garden," Mr Wheal, the brother of Jamie's mother, said. "We don't know exactly what happened, but from the pathologist's report it looks like he fell from a height.
"He got caught up in the rope, which broke his neck, meaning he was unconscious instantly. He effectively hanged."
Jamie was rushed to Southampton General Hospital at about 5pm on Tuesday, where he was pronounced dead.
Mr Wheal said Jamie's parents Sarah, 42, and Richard, 41, and his 11-year-old brother Sam were dealing with his death "as badly as could be expected".
He said: "It's every parent's worst nightmare. He had just gone to play in the tree house after school - it's only about 15 yards from their home.
"Kids have fallen out of trees for hundreds of years. All they usually end up with is a scratch or a bruise. This was just a complete freak accident."
