Sage Stallone, son of actor Sylvester Stallone, has been found dead, The New York Post and TMZ report. The junior Stallone was reportedly found at home in Los Angeles. TMZ reports that his father is, understandably, extremely distraught. The Post spoke with Sage Moonblood Stallone's attorney, who said the death came as a complete shock. "He was in good spirits, and working on all kinds of projects,â€ George Braunstein told the paper. â€œHe was planning on getting married. I am just devastated. He was an extremely wonderful, loving guy. This is a tragedy.â€ TMZ's sources say the cause of death was a prescription drug overdose. The Post reports that his mother, Sasha Czack, had also been notified of her son's passing. Stallone made his acting debut alongside his father in "Rocky V." He went on to act in a number of films, most recently in "Promises Written in Water" in 2010 (he also appeared in "The Agent," a short, and in a television documentary episode on the Rocky films). Sylvester Stallone was in San Diego Thursday to promote "Expendables 2," his new film with Arnold Schwarzenegger. The actors spoke on a panel in Hall H at Comic-Con. I went 4 pages in and didn't find Stallone in any subject lines, I did not read every post made!