Vanessa Hudgens supports Austin Butler as he mourns the death of his mom Credit: JB Lacroix/WireImage

Austin Butler is mourning the death of his mom Lori Butler, who passed away on Thursday, Sept. 11, and girlfriend Vanessa Hudgens is supporting him every step of the way.

The Carrie Diaries star, 23, announced his tragic news of his mom's death to fans via Twitter on Thursday afternoon. A source tells Us Weekly his mom had been battling cancer.

"Lori Butler, my mom, my hero, & my best friend passed away this morning," the heartbroken actor wrote. "Lets all celebrate her. I love you and will miss you every day Mom."

Hudgens, 25, who has been dating Butler since 2011, was evidently devastated by the news, too. Sending a public message of support to her boyfriend, The Frozen Ground actress retweeted his words with the addition "I miss you already mama."

"#ripLoriButler #celebrateLori," the actress added. "Spread the love for Lori."

Hudgen's own mom, Gina Hudgens, also expressed her sympathies and sadness, with a heartfelt message.

"Lori, RIP. You'll be forever alive in our hearts & mind," she tweeted. "You'll always be our angel in heaven watching over us. U will be missed!"