'Grease' Cast Members Pay Tribute to Olivia Newton-John After Her Death: 'One of the Kindest' Souls

Cast members from the 1978 musical film Grease are mourning the loss of their late costar Olivia Newton-John, who died Monday at age 73.

Newton-John's death was announced by her husband, John Easterling, via her official Instagram page. He noted that the late star "passed away peacefully at her Ranch in Southern California," where she was "surrounded by family and friends."

John Travolta — who played Danny Zuko opposite Newton-John's Sandy in Grease — was one of the first to remember the actress by sharing a heartfelt tribute on Instagram alongside a throwback photo of her.

"My dearest Olivia, you made all of our lives so much better," he wrote in the caption. "Your impact was incredible. I love you so much. We will see you down the road and we will all be together again."

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"Yours from the moment I saw you and forever! Your Danny, your John!" Travolta concluded.

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Stockard Channing, who played Pink Lady Betty Rizzo, also remembered her costar on Monday, telling PEOPLE in a statement, "I don't know if I've known a lovelier human being."

"Olivia was the essence of summer – her sunniness, her warmth and her grace are what always come to mind when I think of her," she added. "I will miss her enormously."

Jamie Donnelly, who played Jan, says, "Olivia's heart was as pure as her voice. Her goodness and grace will shine through the ages in her work. I have known her for over 40 years and never heard her say a negative word of anyone or anyone say a negative word of her. What a glorious soloist for the heavenly choir."

Dinah Manoff, who played Marty Maraschino in the film, also honored Newton-John via a statement to PEOPLE following her death.

"As many will tell you, Olivia Newton-John was one of the kindest, most generous souls ever to grace the earth, and I was one lucky Pink Lady to have spent time with her during the filming of Grease," Manoff said. "She brought light and laughter wherever she went. My deepest condolences to her family and friends during their time of great loss."

Following the announcement of Newton-John's death, tributes to the Xanadu superstar came via social media from fellow celebrities, musicians and film stars.

Her husband Easterling, 70, said that Newton-John "has been a symbol of triumphs and hope for over 30 years sharing her journey with breast cancer."

In his post, he wrote, "Her healing inspiration and pioneering experience with plant medicine continues with the Olivia Newton-John Foundation Fund, dedicated to researching plant medicine and cancer. In lieu of flowers, the family asks that any donations be made in her memory to the @onjfoundation."

Newton-John announced in May 2017 that she was diagnosed with breast cancer, which had metastasized to the sacrum. At the time, her team said that Newton-John would be completing photon radiation therapy, in addition to natural wellness therapies after consulting with her medical team at the Olivia Newton-John Cancer Wellness and Research Centre in Melbourne, Australia.

In addition to Easterling, Newton-John is survived by her daughter Chloe Lattanzi; sister Sarah Newton-John; brother Toby Newton-John, nieces and nephews — Tottie, Fiona and Brett Goldsmith; Emerson, Charlie, Zac, Jeremy, Randall, and Pierz Newton-John; Jude Newton-Stock, Layla Lee; Kira and Tasha Edelstein; and Brin and Valerie Hall.