Sylvester Stallone's son Sage has been found dead in his Hollywood apartment.
The 36-year-old's attorney, George Braunstein, has confirmed the tragic news to the New York Post, saying his client's passing is a mystery to him.
He tells the publication, "He was in good spirits, and working on all kinds of projects. He was planning on getting married. I am just devastated. He was an extremely wonderful, loving guy. This is a tragedy."
Sage Stallone's mother, Sasha Czack, has been told the sad news. His father is currently promoting the "Expendables" sequel at Comic-Con in San Diego.
Sage made his acting debut alongside his father in 1990's "Rocky V" but turned down the chance to reprise his role as the movie boxer's son, Robert Balboa, in the 2006 movie "Rocky Balboa." He also starred opposite his father in 1996's "Daylight."