When US father Matt Sooter took a picture of a loving moment between his two children he knew it was probably the last photo they would have together.
The heartbreaking image was shared on Facebook and shows 6-year-old Jackson comforting his 4-year-old sister Addy before she lost her fight with cancer.
"A little boy should not have to say goodbye to his partner in crime, his play mate, his best friend, his little sister," Sooter wrote.
"This isn't how it's supposed to be. But this is the broken world we live in."
In 2016 Addy was diagnosed with Diffuse Intrinsic Potine Glioma, a type of brain tumour that starts in the brain stem and affects the person's muscles, nerves, heart rate and breathing.
Over the next year and a half the 4-year-old had 33 chemotherapy treatments, which stopped the growth of the tumour for about six months. But when it started to grow again the family turned to experimental treatments in Mexico, which cost them over $200,000.
The treatment, which drained fluid from the brain, seemed to help for a time but eventually the tumour continued to spread, news.com.au reported.
"Addy's symptoms have progressed rapidly over the past day and a half. Yesterday she woke up as her spunky playful self," Sooter wrote on Hope for Addy Joy, the page they use to update family and friends on her progress.
"While we still see short instances of our girl she can no longer eat or swallow without difficulty and she's sleeping most of the time now and we've admitted her into inpatient care. Most likely she doesn't have much time left."
Addy tragically died on June 3, just hours after the loving picture between the two siblings was shared.
In the hours before Addy's death Sooter said Jackson was refusing to leave his sister's side.
The tear-jerking photo showing Jackson resting his hand on Addy's head while she clutched at his arm has been shared more than 900 times, and hundreds of people offered their condolences to the grieving family.
"Such a heartbreakingly beautiful picture. I'm so sorry for your incredible loss," one person said.
"This picture speaks volumes. Jackson will cherish this forever! The love between a brother and his sister," another user said.
One added: "This is just heartbreaking to see this darling boy caring for his sister. They should be out playing not this."