Rascal Flatts Star Mourns 'Tragic, Heartbreaking' Loss Of Hayden Panettiere

Jay DeMarcus shared a photo with Hayden Panettiere as he mourned the loss of the late Nashville star.

The Rascal Flatts artist wrote in a caption on Instagram that he'd "just heard the tragic news of Hayden's passing. I had the privilege of working with her several times during her years here in Nashville, this is absolutely heartbreaking.. prayers for the family."

Panettiere died on Sunday (August 16). She was 36. A representative for the actress confirmed in a statement: "It is with profound sadness that we share the tragic passing of our beloved Hayden. 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."

Details emerging since news broke of Panettiere's death indicate that a friend of the Heroes actress found her "unresponsive" at a home in South Carolina on Sunday afternoon. In dispatch audio obtained by TMZ, PEOPLE and other outlets, responders can be heard talking about a possible "overdose," and "cardiac arrest." The preliminary investigation indicates no sign of foul play, according to a spokesperson from the Greenville Police Department, which is investigating Panettiere's death with the Greenville County Coroner's Office. Her official cause of death has not been confirmed as of publication time on Monday morning (August 17).

Among other roles throughout her career, the Palisades, New York-born actress was known for playing Juliette Barnes on Nashville. The musical TV drama premiered in 2012, and the finale aired in 2018. The series also starred Connie Britton, Charles Esten, Clare Bowen, Jonathan Jackson, Sam Palladio, Chris Carmack, Kimberly Williams-Paisley and more. Nashville also featured guest appearances and cameos by Brad Paisley, Carrie Underwood, Luke Bryan, Kasey Musgraves, Sara Evans, Kelsea Ballerini, Chris Young and other real-life country stars.

Panettiere mourned the sudden loss of her younger brother, actor JansenPanettiere, in February 2023. He was 28. The Panettiere - including parents Skip Panettiere and Lesley Vogel - confirmed at the time that Jansen died of "cardiomegaly (enlarged heart), coupled with aortic valve complications. …We sincerely appreciate the outpouring of love and support towards our family as we navigate this unthinkable loss, and ask that we be gifted our privacy during this time of mourning. We love you so much Jansen and you will be in our hearts forever." Shortly after Jansen's passing, his sister placed her hand over her heart in an interview and said, "he's right here with me."