Actress Hayden Panettiere, known for her roles in "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. They located Panettiere, 36, unresponsive and in cardiac arrest. Despite advanced life support measures, resuscitation efforts were unsuccessful, and she was pronounced deceased at 2:32 PM, officials stated.

The coroner's office reported that an autopsy was completed Monday, revealing 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.

Panettiere had been 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 her passing.

Panettiere's representative had previously confirmed her death to ABC News on Sunday, stating that an investigation was ongoing. Her father, Skip Panettiere, issued a statement expressing profound sadness and requesting privacy for the family as they process their loss. He described his daughter as "an incredible light and a force of nature."

Beginning her career as a child star, Panettiere gained widespread recognition for her portrayal of Claire Bennet on the NBC series "Heroes" and later as Juliette Barnes on the musical drama "Nashville." Her film credits include "Remember the Titans," "Raising Helen," "Ice Princess," and "Scream 4."

In May, Panettiere released a memoir, "This Is Me: A Reckoning," in which she candidly discussed her struggles with postpartum depression, addiction, recovery, trauma, domestic abuse, and loss, offering a personal glimpse into her life.

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