Rob Lowe, Mario Lopez and Brad Paisley paid tribute to Olivia Newton-John at a charity event hosted by Los Angeles Dodgers pitcher Clayton Kershaw.

"She was the nicest woman and a true icon for sure. I was sad to hear about her passing," award-winning actor Rob Lowe told Fox News Digital.

Olivia Newton John on the red carpet.

Olivia Newton-John battled breast cancer for 30 years and died at the age of 73. (Getty Images)

The iconic "Grease" star battled breast cancer for 30 years and died "peacefully at her ranch in Southern California" Monday morning, "surrounded by family and friends," according to an Instagram post shared by her family. She was 73 years old.

OLIVIA NEWTON-JOHN DEAD AT 73

"Saved by the Bell" actor Mario Lopez added that Newton-John was "the sweetest person," and "one of the nicest people" he has had the pleasure of interviewing. 

"It's…a sad loss," Lopez remarked. "I have nothing but wonderful memories about her…she was talented and beautiful."

Newton-John was diagnosed with cancer multiple times through the years after first revealing she battled breast cancer in 1992, which she discussed in her 2019 memoir, "Don't Stop Believin.'"

Olivia Newton-John and John Travolta

Australian singer Olivia Newton-John was known for hits including "You're the One That I Want" from the classic film "Grease." (Paramount Pictures/Fotos International)

Country music star Brad Paisley also noted that the Australian singer was a "very kind person" as they both shared the same manager.

"There's a couple of really nice people…that left this earth," Paisley told Fox News Digital. 

"It's rare that I think she was probably nice to everybody she met… sad when that happens, but what a life and what a survivor, too…that's truly a victory in the end."

Olivia Newton John Chloe Lattanzi

Chloe Lattanzi and Olivia Newton John attends the Olivia Newton-John Wellness Walk and Research Run on Oct. 6, 2019 in Melbourne, Australia. The event helps fund cancer research and provide access to world-leading wellness and support care programs for patients within the ONJ Centre. (Photo by Sam Tabone/WireImage) (WireImage)

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On Monday, Dodgers’ star Clayton Kershaw, along with his wife Ellen, hosted their 8th annual "Ping Pong 4 Purpose" charity event, Kershaw’s Challenge, at Dodger’s stadium. 

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The couple founded the charity in 2011 and has raised more than 16 million dollars in the decade since. Kershaw’s Challenge supports at-risk children and families worldwide and has raised funds to lend a hand to beneficiaries in Los Angeles, Africa and Dominican Republic. 

Fox News' Tracy Wright contributed to this report.