A family friend is under investigation and could be to blame for a jet ski accident which left Usher's 11-year-old stepson brain dead, officials revealed Monday (July 9).

The "Scream" singer's stepson, Kyle Grover, is the son of his ex-wife Tameka Foster and according to The Georgia Department of Natural Resources, Kyle was floating on an inner tube with a 15-year-old girl by a pontoon boat on Georgia's Lake Lanier when 38-year-old family friend Jeffrey S. Hubbard ran over both of them.

TMZ reports that at the time of the incident Usher allegedly arranged for for Grover to be flown to the hospital by chartering a plane and a source tells US Weekly that Usher is having a hard time dealing with the tragic accident, "He grew close to Kyle and, of course, that has nothing to do with the situation with Tameka. He loved Kyle. This is a terrible, awful tragedy. Usher is torn up."

Usher's 11-year-old stepson is still in critical condition at Children's Healthcare of Atlanta and according to TMZ he has no brain activity since being admitted while the CBS Atlanta affiliate WGCL-TV says the boy's 15-year-old friend suffered a broken arm and cut on her head.

Although no charges have been filed against Hubbard, Police say charges are pending and confirmed alcohol was not a factor and they don't believe the watercraft malfunctioned.

Usher has two children with Tameka Foster whom he split with in 2009: Usher V, 4, and Naviyd, 3.