Harriet Shelley, the sister of singer George Shelley, has died following a car accident in Bristol.
The 21-year-old died on Saturday night (6 May).
"George and the entire family are devastated and heartbroken at the loss of their beloved, beautiful Harriet," a family statement read.
"They are all together, supporting each other at this difficult time and would appreciate the time and space to do so before they make any further comments."
As a result of the accident on April 28, Harriet suffered serious head injuries and was in intensive care.
She died at Southmead Hospital in Bristol, her family confirmed.
After news of her death, George's former Union J bandmates took to Twitter to offer their condolences and support.
Jaymi Hensley, JJ Hamblett and Josh Cuthbert recalled George's "beautiful and wonderful" sister.
In a further post Jaymi added:
JJ Hamblett added:
While Josh wrote:
Her mum Toni Harris from Clevedon, Somerset told Mail Online that her daughter had been in the "wrong place at the wrong time".
She praised the staff at Southmead Hospital who she said had been "working 24/7" to try to save her daughter.
Harriet had recently graduated with a midwifery degree. Her brother George found fame on the X Factor with his band Union J in 2012, finishing fourth in the competition.