Parents of late Youtube star, Caleb Logan Bratayley, announced his untimely death at the age of 13 on September 29 at his family house in Maryland, U.S.A, have now disclosed the cause of the youngstar's death.

Read: Youngest YouTube star dies at 13

Hours after announcing the unexpected passing of their son, YouTube's Bratayley family has revealed the teen's cause of death.

In an Instagram post shared late Monday, October 5, the Bratayleys (not their real name) said Caleb had died of an "undetected medical condition."

"Caleb's death has raised many questions about how and why this could happen to a seemingly healthy boy," they captioned a photo of the young YouTuber. "Sadly, tests have confirmed today that Caleb passed away from an undetected medical condition. We'll have more definitive answers in the coming weeks but ask that you help us celebrate his life instead of focus on his death."

With this in mind, the family plans to share Caleb's memorial in the same way they've shared so many other moments in the past.

"Due to an outpouring of support and people's hope to be part of his memorial, we have decided to live-stream the ceremony tomorrow [Tuesday, Oct. 6] at 8pm EDT," the caption noted. "Thank you for all your kindness during this difficult time."

The Bratayleys,  have begun to share daily videos about their life in 2010 with their 1.6 million subscribers on their YouTube channel.

The family first announced Caleb's death on Friday, October 2.

"Yesterday at 7:08PM Caleb Logan Bratayley passed away of natural causes," according to the Instagram post. "This has come as a shock to all of us. Words cannot describe how much we will miss him. His incredibly funny, loving, and wonderful spirit made us all fall in love with him as a YouTuber, friend, brother, and son."

His mother later shared a video taken the day before Caleb's death, in which he poses questions to his future self.

Read: Daughter pays touching tribute to late star 1 year after

"Unfortunately Caleb passed away the day after we made this video," a message at the end of the clip shared. "He will never get to meet his future self. None of us will and we are very sad a because he would have been great. Please kiss your kids and tell them you love them every day. You never know what day will be their last."

Watch video below.