It's not an easy day for Vanessa Hudgens.
"I am devastated," Ashley Tisdale, who starred as Sharpay in the 2006 Disney musical drama, wrote. "Just thinking of my girl and praying for her strength today."
She also posted a lengthier message on Instagram, encouraging her fans to tune in and send prayers.
Monique Coleman was one of the first celebrities to share her support for Vanessa and her younger sister, 20-year-old Stella Hudgens, writing, "My deepest condolences @VanessaHudgens @stellahudgens. I love you both so much! You're in my thoughts & prayers."
Hudgens' Spring Breakers co-star Ashley Benson and Sucker Punch co-star Jamie Chung also rallied around her, both tweeting their love and support.
As ET previously reported, Vanessa asked her followers to pray for her dad's healing over Instagram last July, announcing one month later that he was sick with stage 4 cancer
at the Industry Dance Awards in Los Angeles. The news came less than one year after her boyfriend, Arrow
star Austin Butler, lost his mother
to cancer in September 2014. No other details about Greg's death at age 65 have been given yet.
In addition to her former co-stars, many other celebrities, friends and fans also took to social media to send prayers to the Hudgens family and wish Vanessa good luck in the production, which airs on FOX at 7 p.m. ET.