LOS ANGELES, Aug. 18 -- Hayden Panettiere's cause of death remains undetermined after an autopsy found no signs of trauma that contributed to the Heroes and Nashville star's sudden death aged 36.

The actress was found unresponsive at a residence in Greenville, South Carolina, on Sunday, after an acquaintance called 911 at about 1.51pm.

Emergency crews found Panettiere in cardiac arrest and performed advanced cardiac life support, but she was pronounced dead at 2.32pm.

Greenville County coroner Mike Ellis said an autopsy had been carried out and found no trauma contributing to her death.

The cause and manner of death remain pending while additional studies are completed.

Police have previously said there was no evidence of foul play o...