Heartbreaking image reveals siblings' emotional reunion weeks after fatal crash killed parents and baby sister

Two young siblings were reunited in hospital three weeks on from a fatal crash that killed both their parents and baby sister.

A heartbreaking image revealed the moment five-year-old Zachary and eight-year-old Angela, both wearing neck braces, held hands for the first time since the accident on April 7 in Sterling City, Texas.

Their younger brothers Wyatt and Nicholas also survived the crash that killed their parents Jim Alan Clemens and Karisa Brianne Clemens and their two-month-old daughter Juliana, when a passing driver veered into the family's car on a highway, 7 NEWS reports.

"He [Zachary] was able to leave his bed and get into the wheelchair for the first time," wrote the children's mother's aunt Teresa Burrell on a Facebook Fundraiser page.

"He and Angie were able to see each other for the first time.

"Angie has had a lot of brain injuries but she was able to read and sing with us."

Angela, Zachary and Wyatt were critically injured in the accident and are undergoing treatment at a Children's medical centre in Fort Worth.

More than 2000 people have donated a total of $101,750 (USD) to the Facebook page that was set up by Ms Burrell to help with funeral and medical costs.