Ron Howard says he 'had no idea' his 'Happy Days' co-star Erin Moran was ill


Ron Howard was in disbelief about the death of his Happy Days co-star, Erin Moran.

Officials told ET that the 56-year-old actress likely died due to complications of stage four cancer. On Monday's episode of CBS' The Talk, Howard admitted that the death of his former onscreen sister hit him hard.

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"It's been a rough time. Bill Paxton, we lost a while back -- a very good friend," he said. Paxton -- who starred in several of Howard's movies -- died in February due to complications from surgery. He was 61.

"My stepmother, Judy, passed away a couple of months ago," Howard continued. "So, the Erin event really did hit hard and shock. I had no idea she was ill whatsoever."

See photos of Erin Moran:

24 PHOTOS
Erin Moran through the years
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Erin Moran through the years
Actress Erin Moran poses for a portrait in circa 1980. (Photo by Michael Ochs Archives/Getty Images)
American actors Erin Moran and Scott Baio hold each other in a publicity still for the television show 'Joanie Loves Chachi,' in which they play the title characters, 1982. (Photo by Fotos International/Getty Images)
BEVERLY HILLS, CA - JANUARY 30: Actor Scott Baio and Actress Erin Moran attending 39th Annual Golden Globe Awards on January 30, 1982 at Beverly Hilton Hotel in Beverly Hills, California. (Photo by Betty Galella/WireImage)
BEVERLY HILLS, CA - JANUARY 30: Actor Scott Baio and actress Erin Moran attend the 39th Annual Golden Globe Awards on January 30, 1982 at the Beverly Hilton Hotel in Beverly Hills, California. (Photo by Betty Galella/WireImage)
NEW YORK - OCTOBER 25: Actress Erin Moran and Scott Baio attending 1982 American Image Awards on October 25, 1982 at Sheraton Center in New York City, New York. (Photo by Ron Galella/WireImage)
American actors Erin Moran, wearing a wedding dress, and Scott Baio, wearing a tuxedo, pose at an altar in a promotional portrait from the TV program 'Happy Days.' Their characters Joanie and Chachi were married during the show's final season. (Photo by Hulton Archive/Getty Images)
Actress Erin Moran attends 17th Annual Academy of Country Music Awards on April 29, 1982 at Knott's Berry Farm in Buena Park, California. (Photo by Ron Galella/WireImage)
LOS ANGELES - JUNE 7: Actress Pat Klous and actress Erin Moran attend K-Earth 101.1 FM Radio Station Celebrity Charity Basketball Game on June 7, 1986 at Fairfax High School in Los Angeles, California. (Photo by Ron Galella, Ltd./WireImage)
Actress Erin Moran attends the premiere of The Evening Star on December 13, 1996 at Mann National Theater in Westwood, California. (Photo by Ron Galella, Ltd./WireImage)
Actress Erin Moran and Steve Fleischman attend Ringling Brothers Circus Variety Club Children's Benefit on August 7, 1997 at the Great Western Forum in Inglewood, California. (Photo by Ron Galella, Ltd./WireImage)
Actress Erin Moran attends American Image Awards on October 25, 1982 at the Sheraton Center in New York City. (Photo by Ron Galella/WireImage)
Actress Erin Moran attends Benefit Basketball Game on June 7, 1986 at the Fairfax High School in Los Angeles, California. (Photo by Ron Galella, Ltd./WireImage)
Actress Erin Moran attends Third Annual Connie Stevens Celebrity Fashion Show on June 8, 1986 at the Ambassador Hotel in New York City. (Photo by Ron Galella, Ltd./WireImage)
391064 10: Actress Erin Moran attends the Hollywood Collectors & Celebrities Show June 23, 2001 at Beverly Garland''s Holiday Inn in North Hollywood, CA. (Photo by Getty Images)
LOS ANGELES, CA - MARCH 14: Actress Erin Moran attends a launch party for DeeDee Bigelow's episode on Surreal Life at Mood supperclub on March 14, 2007 in Los Angeles, California. (Photo by Chad Buchanan/Getty Images)
Actress Erin Moran attends Night of 100 Stars Gala on November 2, 1983 at the Bel Air Hotel in Los Angeles, California. (Photo by Ron Galella, Ltd./WireImage)
NORTH HOLLYWOOD, CA - MAY 6: (L-R) Actresses Erin Moran, Marion Ross, Cloris Leachman and Holland Taylor attend 'A Mother's Day Salute to TV Moms' at the Academy of Television Arts & Sciences May 6, 2008 in North Hollywood, California. (Photo by David Livingston/Getty Images)
NORTH HOLLYWOOD, CA - MAY 6: Actress Erin Moran (R) and her husband Steven Fleischmann attend 'A Mother's Day Salute to TV Moms' at the Academy of Television Arts & Sciences May 6, 2008 in North Hollywood, California. (Photo by David Livingston/Getty Images)
NORTH HOLLYWOOD, CA - MAY 6: Actress Erin Moran attends 'A Mother's Day Salute to TV Moms' at the Academy of Television Arts & Sciences May 6, 2008 in North Hollywood, California. (Photo by David Livingston/Getty Images)
HOLLYWOOD - SEPTEMBER 24: Actress Erin Moran arrives at the Fox Reality Channel Really Awards at the Avalon Hollywood club September 24, 2008 in Hollywood California. (Photo by Frazer Harrison/Getty Images)
HOLLYWOOD, CA - SEPTEMBER 24: Actress Erin Moran and guest attend the FOX Reality Channel Really Awards on September 24, 2008 at the Avalon Hollywood club in Hollywood, California. (Photo by Getty Images for FOX)
LOS ANGELES, CA - APRIL 23: Actress Erin Moran at the 4th Annual LA Jewish Film Festival Opening Night Gala Event at the Writer's Guild Theater on April 23, 2009 in Beverly Hills, California. (Photo by Amy Graves/WireImage)
NORTH HOLLYWOOD, CA - JUNE 18: Actress Erin Moran arrives at the Academy Of Television Arts & Sciences' 'Father's Day Salute To TV Dads' on June 18, 2009 in North Hollywood, California. (Photo by Frazer Harrison/Getty Images)
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Howard and Moran played siblings Joanie and Richie Cunningham on Happy Days, and the 63-year-old actor-director has fond memories of working with her. "She was always the kid on the set, in a way," he reminisced. "When I think of her then, which is how I choose to think of her, she was this feisty, spirited little girl."

Howard also recalled a Happy Days rehearsal that turned into a messy, shaving cream fight. "It was kind of a boys club, we had all the guys goofing around," he said. "There was a lot of hi-jinks and goofy frat stuff going on. But I do remember a particular moment where we were in a rehearsal, in our rehearsal clothes, and somehow it was kind of turning into a shaving cream fight. And she did sneak up behind Henry Winkler with a pretty good shaving cream pie, and she got him."

WATCH: Happy Days Actress Erin Moran Likely Died of Cancer, Officials Say

Upon hearing the news of Moran's death over the weekend, Howard sent out a heartfelt tweet in honor of his late co-star. "Such sad sad news," he wrote. "RIP Erin. I'll always choose to remember you on our show making scenes better, getting laughs and lighting up TV screens."

Winkler -- who played Fonzie on Happy Days -- also showed his gratitude to Moran's fans. "THANK YOU ALL for your heartfelt and generous messages about untimely and tragic death of Erin," he tweeted on Tuesday. "The Happy Days family will never forget her."

Celebrities that died in 2016:

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Celebrities who died in 2016
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Celebrities who died in 2016

Glenn Frey (67): Nov. 6, 1948 - Jan. 18, 2016 

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George Michael

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Merle Haggard

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Carrie Fisher

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Natalie Cole (65): Feb. 6, 1950 - Dec. 31, 2015

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Pat Harrington Jr. (76): Aug. 13, 1929 - Jan. 6, 2016

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Zsa Zsa Gabor

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Michael Galeota (31): Aug. 28, 1984 - Jan. 10, 2016

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David Bowie (69): Jan. 8, 1947 - Jan. 10, 2016 

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Alan Rickman (69): Feb. 21, 1946 - Jan. 14, 2016 

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Dan Haggarty (74): Nov. 19, 1941 - Jan. 15, 2016

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Tommy Kelly (90): April 6, 1925 - Jan. 26, 2016

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Abe Vigoda (94): Feb. 24, 1921 - Jan. 26, 2016 

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Joe Alaskey (63): April 17, 1952 - Feb. 3, 2016

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Maurice White (74): Dec. 19, 1941 - Feb. 4, 2016

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Vanity (57): Jan. 4, 1959 - Feb. 15, 2016

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George Gaynes (98): May 3, 1917 - Feb. 15, 2016

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Angela "Big Ang" Raiola (55): June 30, 1960 - Feb. 18, 2016

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Harper Lee (89): April 28, 1926 - Feb. 19, 2016

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Lee Reherman (49): July 4, 1966 - Feb. 29, 2016

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Bud Collins (86): June 17, 1929 - March 4, 2016

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Joey Feek (40): Sept. 9, 1975 - March 4, 2016

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Nancy Reagan (94): July 6, 1921 - March 6, 2016

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Sir George Martin (90): Jan. 3, 1926 - March 8, 2016

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Garry Shandling (66): Nov. 29, 1949 - March 24, 2016


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Patty Duke (69): Dec. 14, 1946 - March 29, 2016

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Daisy Lewellyn (36): Jan. 15, 1980 - April 8, 2016 

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David Gest (62): May 11, 1953 - April 12, 2016 

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Joanie "Chyna" Laurer (46): Dec. 27, 1969 - April 20, 2016 

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Prince (57): June 7, 1958 - April 21, 2016

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Rickey Smith (36): May 10, 1979 - May 5, 2016 

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William Schallert (93): July 6, 1922 - May 8, 2016

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Tonita Castro (63): 1953 - May 8, 2016

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Morley Safer (84): Nov. 8, 1931 - May 19, 2016 

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Janet Waldo (96): Feb. 4, 1920 - June 12, 2016

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Muhammad Ali (74): Jan. 17, 1941 - June 3, 2016 

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Theresa Saldana (61): Aug. 20, 1954 - June 6, 2016 

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Ronnie Claire Edwards (83): Feb. 9, 1933 - June 14, 2016

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Anton Yelchin (27): March 11, 1989 - June 19, 2016

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Noel Neill (95): Nov. 25, 1920 - July 3, 2016

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Bill Cunningham (87): March 13, 1929 - June 25, 2016

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Teddy Rooney (66): April 13, 1950 - July 2, 2016

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Garry Marshall (81): Nov. 13, 1934 - July 19, 2016

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Gene Wilder (83): June 11, 1933 - Aug. 29, 2016

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Rene Angelil (73): Jan. 16, 1942 - Jan. 14, 2016

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Alexis Arquette (47): July 28, 1969 - Sept. 11, 2016

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Robert Vaughn (83): Nov. 22, 1932 - Nov. 11, 2016

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Gwen Ifill (61): Sept. 29, 1955 - Nov. 14, 2016

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Florence Henderson (82): Feb. 14, 1934 - Nov. 24, 2016

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Alan Thicke (69): March 1, 1947 - Dec. 13, 2016

(Photo by Andrew Chin/Getty Images)

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