Tragic news for Usher and his family.

The Grammy-winning singer's 11-year-old stepson, Kyle Glover, has been declared brain dead after being accidentally struck with a jetski, TMZ reports.

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Kyle, the son of Usher's ex-wife Tameka Foster, was riding an inner tube on Lake Lanier in Atlanta, GA on Saturday when a jetskier hit him -- striking him in the head and knocking him unconscious.

Kyle was airlifted to a nearby hospital, where Usher, 33, is said to have joined him Sunday evening. TMZ reports that Kyle has registered no brain activity since being admitted.

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Authorities are investigating the accident, although alcohol has already been ruled out as a contributing factor.

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Usher (real name: Usher Terry Raymond IV), 33, divorced Tameka in late 2009 after two years of marriage. In addition to Kyle, Tameka's child from a previous relationship, the duo share sons Usher Raymond V, 4, and Naviyd, 3. The former spouses have been in a protracted custody dispute.

This article originally appeared on Usher's Stepson, 11, Declared Brain Dead After Jet Ski Accident: Report