The 36-year-old son of Sylvester Stallone has been found dead, leaving the actor grief-stricken, his publicist said.
Details surrounding the death of Sage Stallone were not immediately available.
"Sylvester Stallone is devastated and grief-stricken over the sudden loss of his son," publicist Michelle Bega said in a statement.
"His compassion and thoughts are with Sage's mother, Sasha."
Los Angeles police said they were dispatched to investigate a death at a home on Mulholland Terrace but could not confirm the person's identity or offer details.
Sage Moonblood Stallone was the oldest of Sylvester Stallone's children and co-starred with his father in two films.
He was the first of two sons Stallone had with first wife Sasha Czack.
Sage Stallone made his acting debut in 1990's Rocky V and also appeared with his father in 1996's Daylight. He also directed the 2006 short Vic, which was screened at the Palm Springs Film Festival.
A Los Angeles County coroner's investigator said there were no signs of foul play.
Assistant Chief Coroner Ed Winter said prescription bottles were recovered in the investigation, but he could not say what kind or how many, and whether they had a role in his death. Mr Winter said Sage Stallone was found unresponsive by an employee and a relative, and police arrived and confirmed he was dead. No suicide note was found.