Following a decade-long battle with cancer, David Cook's brother, Adam, died yesterday.
The American Idol winner made the difficult announced this morning, prior to the Race for Hope 5K in Washington, D.C.
"I actually lost my brother yesterday to a brain tumor and I couldn't imagine being anywhere else right now," Cook told the crowd at the brain cancer research benefit, at which Cook served as the grand marshal and competitor, as his team had raised more than $40,000.
Adam Cook had battled the disease throughout Cook's American Idol run last year.
Our thoughts and prayers go out to David and his family.