Actress Hayden Panettiere, known for her roles on "Heroes" and "Nashville," was found in cardiac arrest prior to her death, the Greenville County Coroner's Office confirmed Monday.

First responders were dispatched to a residence in Greenville, South Carolina, on Sunday following a 911 call. Upon arrival, they located Panettiere, 36, unresponsive and in cardiac arrest. Despite advanced life support measures initiated by emergency personnel, resuscitation efforts were unsuccessful.

Officials stated that Panettiere was pronounced deceased at 2:32 PM on Sunday. An autopsy was completed on Monday, and the coroner's office reported no signs of trauma that would have contributed to her death. The official cause and manner of death are pending further investigation and the completion of additional studies.

Authorities have indicated that Panettiere was temporarily staying at the residence where she was found. The coroner's office and the Greenville City Police Department have launched a parallel investigation into the circumstances surrounding her passing.

Panettiere's representative had previously confirmed her death to ABC News on Sunday, acknowledging that an investigation was underway. Her father, Skip Panettiere, shared a statement expressing profound sadness and requested privacy for his family during this difficult time.

"She was an incredible light and a force of nature who brought immeasurable love and joy to all who knew her -- and to the millions who watched her onscreen," her father said. Panettiere began her acting career as a child star, achieving widespread recognition for her performances as Claire Bennet in the NBC series "Heroes" and Juliette Barnes in the musical drama "Nashville."

Her career also included notable roles in films such as "Remember the Titans," "Raising Helen," "Ice Princess," and "Scream 4." In May, Panettiere released a memoir titled "This Is Me: A Reckoning," in which she candidly discussed personal struggles including postpartum depression, addiction, recovery, trauma, domestic abuse, and loss.

Panettiere was the mother of one child, a daughter named Kaya Klitschko, born in 2014. She had her daughter with her ex-fiancé, heavyweight champion Wladimir Klitschko.