Hayden Panettiere died from drug mix including fentanyl

According to the Greenville County Coroner's office, Panettiere died as a result of toxic effects of multiple drugs, including fentanyl, 4-ANPP, Alprazolam, Methocarbamol and Quetiapine.

The manner of her death was ruled an accident.

The Coroner's office described being called to an Airbnb property in Greenville County shortly before 2pm in the afternoon local time to find a woman unresponsive and in cardiac arrest.

She could not be resuscitated and she was pronounced dead a short time later.

"The decedent has been identified as Hayden Leslie Panettiere, 36, of California. Panettiere was found unresponsive inside the residence, where she had been temporarily staying," the statement read.

"An autopsy was completed by a Board Certified Forensic Pathologist. At autopsy no signs of trauma were discovered that would have contributed to the death.

"The cause of death has been ruled as toxic effects of fentanyl, 4-ANPP, Alprazolam, Methocarbamol, and Quetiapine. The manner of death has been ruled accident."

It was previously revealed that Panettiere's on/off boyfriend, Brian Hickerson, had handed first responders a bag of her prescription medications when they arrived at the apartment they had been staying at when she died. 

Around 150 of her friends and family members gathered at a church in Malibu, California, on Saturday for a special celebration of life ceremony.

The service was described as "emotional and beautiful" and saw Connie Britton and Charles Esten give speeches, while the Nashville actor also sang one of Panettiere's songs from their show, accompanied by a band at the church.

Among those in attendance were Paris Hilton, Evan Ross, Lennon Stella and Jonathan Jackson.

Hayden's on/off boyfriend and his brother, Zach Hickerson - who were both present at the South Carolina Airbnb where she died - were not invited to the service.

But sources close to the brothers previously told TMZ they recognised the sensitivity surrounding the service and were not challenging the organisers' decision to exclude them.

The sources added the brothers hoped the gathering would be a "beautiful celebration of Hayden, her life and her legacy".