Such unfortunate news for Austin Butler. Yesterday (Sept. 11), 'The Carrie Diaries' actor took to Twitter to make a sad announcement.

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

Austin's girlfriend of two years, Vanessa Hudgens, retweeted his message with the sentiment, "I miss you already mama."

In an additional tweet, the former 'High School Musical' star added, "#ripLoriButler #celebrateLori spread the love for Lori."

According to Us Weekly, Vanessa's mother Gina Hudgens also expressed her sorrow on Twitter, posting, "Lori, RIP. You'll be forever alive in our hearts & mind. You'll always be our angel in heaven watching over us. U will be missed!"

A source tells Us that Austin's mom had been battling cancer.

PopCrush sends our thoughts to Austin, his family and his friends during this sad time.