Hilary Duff shared a heartfelt tribute to the late Hayden Panettiere on Tuesday, remembering their shared past as young actors navigating the complexities of Hollywood. Panettiere died on Sunday at the age of 36.

"Sweet Hayden," Duff wrote in an Instagram post. "Really tough hearing this news. We lost touch through the years, but I will always remember you as so hardworking and effervescent, with that big, gorgeous smile."

Duff recalled moments from decades ago when she and Panettiere were both emerging child stars. "I remember staying up late, chatting and gossiping, and connecting because we were part of such a small sliver of people who actually understood the strange lot in life we were navigating," she said. "We were so young, with no real idea how to make sense of any of it."

Both actresses rose to prominence around the same time. Duff starred in the Disney Channel series "Lizzie McGuire" from 2001 to 2004 and appeared in films like "Cheaper by the Dozen" (2003) and "A Cinderella Story" (2004). Panettiere was known for her roles in soap operas such as "One Life to Live" and "Guiding Light," as well as the 2000 film "Remember the Titans."

Duff concluded her tribute by expressing her sorrow and sending condolences. "I so deeply wish this wasn't the end for you. Sending a heart full of love to your family, the many people you impacted and everyone who loved you. Rest easy."

Duff was among several peers of Panettiere who publicly mourned the actress's passing. Actress Alexa PenaVega referenced the premature deaths of other young stars earlier in the year, including Michelle Trachtenberg and Daveigh Chase, when memorializing Panettiere. "These aren't just names from my childhood," PenaVega stated. "They're girls I grew up alongside, sharing a world that was exciting and also incredibly hard. We were kids navigating something so big, and not everyone had the foundation or support they deserved."

Solange Knowles, who co-starred with Panettiere in "Bring It On: All or Nothing," wrote, "Rest in peace Hayden ... in peace, because you are so deserving of it ... We had so many parallels in our lives, and the world watched u so courageously live in your radical truth telling your story. We watched your endless quest for vulnerability, and healing."

Paris Hilton described Panettiere as "so talented, strong, kind and full of so much love and light," adding, "I’ll always cherish our friendship, all the memories we shared, and the special moments we had together."

Emma Roberts offered her respects, saying, "Rest in peace my sweet friend. You are so loved and you will be forever missed."

Panettiere's father, Skip Panettiere, announced her death on Sunday, stating, "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. We ask for privacy as our family takes time to process this unimaginable loss."

Authorities in Greenville, South Carolina, responded to a report of an unresponsive female at an apartment, which was subsequently determined to be Panettiere. Lifesaving measures were attempted before the actress was declared deceased. Officials stated that no signs of trauma or foul play were evident in the ongoing investigation into her death, which appears to have been related to a drug overdose.