Sylvester Stallone, who is out in San Diego promoting his upcoming sequel The Expendables 2 while at Comic-Con 2012, was struck with sad news this afternoon when he learned that his son, Sage Stallone, had passed away.

The actor-filmmaker was 36 years of age at the time of his passing. A cause of death has not been confirmed, but Sage's body was found in his Los Angeles apartment, with a bottle of pills recovered from the scene. The type of pill has not been reported, but it is believed that the death was caused from an accidental overdose on prescription medication.

At this time, there is no evidence of foul play, and there is no reason to believe that this was a suicide. Sage is said to have been in good spirits in recent weeks, working on many projects, and that he was planning to marry soon. Sylvester Stallone has reportedly been a wreck ever since receiving the news of his son's passing.

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Sage Stallone got his start in Hollywood by playing Rocky Balboa Jr. in Rocky V. After playing several small parts in various projects throughout the years, the actor turned to directing and producing short films.

Sage Stallone's case has already been turned over to the Los Angeles Coroner.

B. Alan Orange at Movieweb
B. Alan Orange