Kaley Cuoco gets emotional recalling her onscreen dad John Ritter's death: 'He's gone'

Kaley Cuoco is still emotional recalling the real-life death of her onscreen dad, 18 years later.

Recalling her work with the late John Ritter, who died in 2003 after a medical emergency on the set of their ABC sitcom, "8 Simple Rules for Dating My Teenage Daughter," Cuoco said the actor was " like no one I've ever met" during ABC's docuseries "Superstar," which on Wednesday aired an episode about Ritter's career and legacy.

"The most generous man, the most fun," she added.

"8 Simple Rules," which ran from 2002 to 2005, starred Ritter as patriarch Paul Hennessy opposite Cuoco as Bridget, the eponymous teenage daughter. The actress recalled her first table read, to which she showed up wearing a spaghetti strap top and shorts that were "way too short."

"In comes John, and I go, 'Hi, I'm playing your daughter,' " she said. "He goes, 'Hold on' and he takes his jacket and puts it over me. He goes, 'Never dress like that again.' And right then, he was my dad."

Cuoco added: "He treated me like his own daughter. He treated all of us kids like that. It was pretty incredible."

More: Kaley Cuoco celebrates Golden Globes loss with pizza, champagne on her kitchen floor

In September 2003, the cast was filming an episode with Ritter's friend, Henry Winkler, serving as a guest star. Cuoco described Ritter as a "kid in the candy store: All of his best friends were there on the set."

"It was a wild week," she said. "And then Thursday came."

Ritter noticed he was sweating a lot and needed water, Winkler remembered from that day. He was also nauseous and having chest pains, noted his wife, Amy Yasbeck. She later got a phone call from her husband saying he was being taken to the hospital.

Doctors initially thought the actor was suffering from a heart attack, which dictated the type of treatment he got. But he was actually experiencing an aortic dissection – a "deadly tear in the large artery that carries blood away from the heart," per the John Ritter Foundation – which would have required another course of action.

Just days before Season 2 of "8 Simple Rules" began airing, Ritter died Sept. 11, 2003, at age 54.

"I just heard screaming, and I looked over and I see all these people and everyone is just hysterical," Cuoco said, her voice breaking. " 'He's gone. He's gone.' And I was like, 'Who's gone? '"

"It was so sudden, so shocking, so sad," Winkler said of returning to set the day after. "We all gathered on the soundstage to be together, to mourn together for a moment.

Quarantine Diaries: Henry Winkler is eating dinner mid-day and waiting to hug his grandkids again

The cast and crew were was "just crying, bawling and then people started telling stories," Cuoco said.

"I'll never forget, there was the mailman at Warner Bros. and he was like, 'I'd like to speak.' He goes, 'I used to deliver the mail here. John would always say hi to me,' and I was like, 'Of course he did.' "

Ritter's legacy, to Cuoco, is that of a generous, funny man. She jokes from time to time that "What would Jesus do?" bracelets were really "What would John do?" bracelets.

"What would John do, you guys? How would he react to this?" she asked. "Probably with kindness, probably with a goofy smile."

Interview: How Kaley Cuoco moved on from sitcom past to serve up racy sex scene in 'Flight Attendant'

This article originally appeared on USA TODAY: John Ritter special: Kaley Cuoco, Henry Winkler on actor's death