Former Happy Days actors Ron Howard and Henry Winkler have led tributes to their co-star Erin Moran, who has died at the age of 56.
Moran played Joanie Cunningham in the hit sitcom as well as its spin-off Joanie Loves Chachi.
Howard, who played her older brother Richie Cunningham but is now a film director responsible for blockbusters including Apollo 13 and The Da Vinci Code, wrote on Twitter: "Such sad sad news.
"RIP Erin. I'll always choose to remember you on our show making scenes better, getting laughs and lighting up tv screens."
Winkler, who is best remembered as Happy Days heartthrob Arthur "The Fonz" Fonzarelli, wrote: "OH Erin ... now you will finally have the peace you wanted so badly here on earth ... Rest In It serenely now.. too soon."
The sheriff's department in Harrison County, Indiana, said a dispatcher "received a 911 call about an unresponsive female. Upon arrival of first-responders, it was determined that Erin Moran Fleischmann was deceased. An autopsy is pending."
Moran joined the Happy Days cast in 1974 when she was 13 and in 2009 she told Xfinity: "What happened with all of us was like we were this family.
"It was so surreal with all the cast members ... They were my family, get it?"
The actress also appeared in The Love Boat, Murder, She Wrote, The Waltons and Diagnosis Murder.
In 2012 she received a settlement from US network CBS after joining various Happy Days cast members in a legal action claiming they were owed money from merchandising revenue.