The family of a 5-year-old boy have been left heartbroken after he suddenly and inexplicably passed away in his sleep.

Cruz passed away on May 11 from a condition similar to SIDS called sudden unexplained death in childhood (SUDC), which, as the name suggests, there is no explanation for the child’s untimely death.

The Red Nose Foundation says SUDC is rare – occurring mainly in toddlers with an incidence of 1.2/100,000 in the United States.

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The heartbroken family revealed that he went to sleep as he normally would and had no prior illnesses or injuries.

In organising a GoFundMe, the family said Cruz was a “beacon of love and light”.

“He was a warrior who filled our lives with joy and laughter,” they said.

“His absence has left an unimaginable void in our family, one that can never be filled.”

Amid the grief, the family say they have been met with a “harsh reality” that his death has brought upon them.

“Giving Cruz the farewell he deserves has come with a financial burden,” they said.

“Cruz’s parents are not only navigating the overwhelming pain of losing their boy, but they are also caring for their two other children while my brother has been unable to return back to work due to their loss.”

The family hopes that the generosity of others will provide them with some “comfort and relief” while they are in mourning.

“Your kind and compassionate gesture will make a world of difference,” they wrote.