Hilary Duff shared an emotional tribute to Hayden Panettiere on Tuesday, two days after the actress's death.

Duff, 38, reminisced about her friendship and bond with Panettiere as fellow child stars in the early 2000s. "Sweet Hayden. Really tough hearing this news," Duff wrote on Instagram. "We lost touch through the years but I will always remember you as so hardworking and effervescent, with that big, gorgeous smile."

Duff and Panettiere, who did not star in any projects together, were photographed at multiple events over the years. Both began their careers at a young age: Duff rose to fame as the title character in Disney Channel's "Lizzie McGuire," which premiered in 2001 when she was 13. Panettiere filmed her breakthrough role as Sheryl Yoast in the 2000 Walt Disney Pictures film "Remember the Titans" at age 10.

"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.. so young, with no real idea how to make sense of any of it," Duff recalled.

"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," Duff concluded her post, adding, "rest easy."

Panettiere died Sunday after an apparent overdose in an apartment in Greenville, South Carolina, according to 911 dispatch audio. Paramedics responded to a call about an "unidentified female" in "cardiac arrest" and performed CPR. She was pronounced dead at 2:32 p.m. local time. She was 36 years old.

Panettiere's estranged mother, Lesley Vogel, told NBC News that her daughter was an "amazingly talented person" and that young people growing up in the entertainment industry often struggle and "find the wrong path."

Her father, Skip Panettiere, previously shared in a statement to Page Six that she was "an incredible light and a force of nature who brought immeasurable love and joy to all who knew her."