Doctors have declared Usher’s stepson brain dead following a jet skiing accident in Georgia’s Lake Lanier, TMZ reports.

Kyle Glover – the 11-year-old son of Usher’s ex-wife Tameka Foster – and an unidentified 15-year-old girl were struck by a jet ski while inner tubing Friday. Kyle has shown no signs of brain activity since being airlifted to an Atlanta hospital, according to TMZ. His friend was treated for a cut on her head and a broken arm.

Celebrity friends, including Russell Simmons and Fantasia Barrino, have taken to Twitter to offer their support.

The accident is under investigation.