The Bratayley family, known for their extremely popular YouTube channel, has revealed 13-year-old Caleb Logan died of an undetected medical condition.

The YouTube world was shocked to learn of the young Bratayley family member’s death late last week, and though they revealed at the time Caleb died of natural causes, fans still had many questions.

In an Instagram post shared late Monday, the family wrote: “Caleb's death has raised many questions about how and why this could happen to a seemingly healthy boy. 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.”

The family went on to explain they will be streaming a memorial service for Caleb so his fan base can mourn him along with the family.

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

The death came as a shock to fans of the Bratayley YouTube channel. The channel has more than 1.6 million subscribers and several videos the family has posted have garnered more than 3 million views.

Last week, the Bratayleys—who use a false last name for their YouTube productions—revealed Caleb had suddenly died, one day after filming an episode for the family’s YouTube channel. That video was shared on their channel along with a message, “It is with our deepest sorrow to report that the Instagram announcement was indeed true. In addition to our desire to give the Internet community the chance to begin the grieving process, we also wanted to post this video to show a healthy and happy Caleb doing what he loved.”