Original "Sesame Street" cast member Bob McGrath says he and castmates Roscoe Orman and Emilio Delgado have been released from the show, after more than four decades.

The 84-year-old McGrath, who also goes by "Bob" on the show, suggested to an audience at Florida Supercon that the change was a result of the show moving to HBO. "They let all of the original cast members go," McGrath said, calling it a "major turnaround." He quickly clarified that not all cast members were let go, as Alan Muraoka and Chris Knowings will remain with the show.

"Sesame Street" was quick to address McGrath's comments in a statement released on Twitter Thursday. "Bob McGrath, Emilio Delgado ('Luis') and Roscoe Orman ('Gordon') remain a beloved part of the Sesame family and continue to represent as at public events," the statement read. "They are a treasured part of Sesame Street."

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Roscoe Orman is shown as Gordon on 'Sesame Street.'

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Bob McGrath is shown on 'Sesame Street.'

The show added that it is "constantly evolving" its content, curriculum and characters to meet the needs of children. "As a result of this, our cast has changed over the years, though you can still expect to see many of them in upcoming productions."

"Sesame Street" also denied McGrath's suggestion that HBO was involved in its creative decisions. "HBO does not oversee the production," the statement said.

McGrath was part of the original cast when the show launched in 1969, and is well-known for such iconic songs as "Who are the People in Your Neighbourhood?"  and "One of These Things is Not Like the Other."  Orman, 72, has played "Gordon" on the show since 1974, while Delgado, 76, has appeared as "Luis" the handyman since 1971.

McGrath's claim that the trio had been let go touched off a firestorm of outrage on social media, with some accusing "Sesame Street" and HBO of ageism.

Pop culture expert Eric Alper, who did public relations for "Sesame Street," says he's not surprised by the outrage. However, he points out that most of the outrage came from nostalgic adults, and not from children.

"My generation grew up watching it, and then we put our kids in front of the television set or YouTube and pretend that they're going to care about it just as well," Alper told CTV News Channel. He added that a lot of children simply don't care the same way, "because they want to have their own shows and their own moments and learn at their own level."

Alper said part of him "died" when he found out about it, but he said change is also a good lesson to teach kids. "People come and go," he said.