Rocker Tom Petty died in October due to "multisystem organ failure" brought on by an accidental overdose of seven medications, the Los Angeles County Medical Examiner's office said Friday.

The coroner's office attributed Petty's death at the age of 66 to a "mixed toxicity" of fentanyl, oxycodone, generic Restoril, generic Xanax, generic Celexa, acetyl fentanyl, and despropionyl fentanyl.

The medical examiner's report lists the manner of death as "accidental."