Story highlights She played the kid sister of Richie Cunningham on "Happy Days"

She was found unresponsive Saturday

(CNN) Popular actress Erin Moran, a mainstay on TV from the late '60s to the mid-'80s and best known for her kid-sister role in the sitcom "Happy Days," has died. She was 56.

Authorities in Indiana found her body Saturday afternoon after getting a 911 call at 4:07 p.m. for "an unresponsive female," the Harrison County Sheriff's Department said.

"Upon the arrival, it was determined that the female was Erin Marie Moran-Fleischmann. First responders determined that she was deceased and an autopsy is pending," the department said.

Moran was cast as Joanie Cunningham, the younger sister of Richie Cunningham, who was played by Ron Howard, a child actor who is now a famed director.

"Such sad sad news ... I'll always choose to remember you on our show making scenes better, getting laughs and lighting up TV screens," Howard wrote on Twitter.

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