Former child star who played Joanie Cunningham in the 70s sitcom “Happy Days” and its spin-off series in the 80s “Joanie Loves Chachi,” has died at age 56 due to unknown cause.

On Saturday afternoon, 911 received a call about an “unresponsive female.”

“Upon arrival of first responders, it was determined that Erin Moran Fleischmann was deceased. An autopsy is pending,” said the statement from the sheriff’s department in Harrison County, Indiana.

Hailing from Burbank, California, Moran began acting in TV and movies before she was 10 years old. She had nearly a decade’s worth of experience when she was cast in 1974 in the hit series “Happy Days” as Joanie Cunningham, the younger sister of high school student Richie Cunningham, played by Ron Howard.

Moran, Howard, and Henry Winkler, who played tough guy Arthur “The Fonz” Fonzarelli, were the series populars. The two actors expressed their condolences to their co-star on Twitter.