Posted 1 hour agoSubscribe to BuzzFeed Daily NewsletterCaret Down"The Walking Dead" Star Kelley Mack's Death Was "Very Unexpected," And She'd Been Auditioning For Work As Recently As JuneKelley tragically died at age 33 following a 7-month cancer battle.by Stephanie SoteriouBuzzFeed StaffFacebookPinterestLink On Tuesday, the sad news broke that actor Kelley Mack had died at the age of 33 - just seven months after being diagnosed with glioma of the central nervous system, which is a type of cancer. Barry Brecheisen / Getty Images Kelley's sister confirmed that she had died on Saturday in an emotional Instagram post that was shared to her profile. "It is with indelible sadness that we are announcing the passing of our dear Kelley. Such a bright, fervent light has transitioned to the beyond, where we all eventually must go," the post began. "Kelley passed peacefully on Saturday evening with her loving mother Kristen and steadfast aunt Karen present." View this photo on Instagram Instagram @itskelleymack / Via instagram.com "Kelley has already come to many of her loved ones in the form of various butterflies 🦋 ❤️. She will be missed by so many to depths that words cannot express," the post went on. "She would want you all to know how much she loves you. And as her sister, I want you all to know how brave that tough SOB was, especially when she decided to make the leap to be reunited with God. I'm so fucking proud of her." Amanda Edwards / Getty Images And now, Kelley's reps have confirmed that the star's death was a complete shock, and that she'd been auditioning as recently as June. Barry Brecheisen / Getty Images The rep told People that they were "totally surprised" by Kelley's death, adding: "We had no idea the turn it took and it was very unexpected." Amanda Edwards / Getty Images TMZ was the first to report this, with this publication also stating that Kelley had a "nice recovery" after undergoing treatment for glioma in February before relapsing shortly before her death. She is said to have told her team she needed to take a break from auditioning in early July. Kelley shared her cancer diagnosis with her Instagram followers on Jan. 3, where she explained that she started suffering "persistent lower back pain" in September. She added: "A few weeks later, I had neuropathic itching in my right quad. And then, the shooting pains in my legs and back began, which resulted in me having to sleep in a recliner for a month because laying down was too painful. On Thanksgiving Eve, I had emergency MRIs done at the hospital, which revealed an abnormal mass in my spinal cord. Fast forward to now - I have been diagnosed with #diffusemidlineglioma, an extremely rare type of #astrocytoma #cancer. Due to the biopsy surgery on my spinal cord, I have lost the use of my right leg and most of my left leg, so I now get around with a walker and a wheelchair." View this photo on Instagram Instagram @itskelleymack / Via instagram.com "I am determined and know that this will eventually be a short chapter in my long book," she poignantly added at the time. "The positivity, love and prayers that are being sent my way already is overwhelming and I feel it all. Thank you so much ❤️❤️" View this photo on Instagram Instagram @itskelleymack / Via instagram.com On March 14, Kelley revealed that she had finished proton radiation treatment and been undergoing physical therapy. She wrote: "Overall, this journey has not been easy, but things are getting better - improvements are tough to see when you're in the thick of it." View this photo on Instagram Instagram @itskelleymack / Via instagram.com And on March 26, the star shared a video of herself proudly walking up some stairs with assistance, saying that "it's a big deal" for her. View this photo on Instagram Instagram @itskelleymack / Via instagram.com Kelley was best known for playing Addy in Season 9 of The Walking Dead, starring in five episodes between 2018 and 2019. The show's director and other stars are among those to have paid tribute to Kelley since news of her death broke. Fox Kelley also played Penelope Jacobs in Chicago Med, and appeared in 9-1-1. A recognition and remembrance of Kelley's life will be held in her home state of Ohio on Aug. 16, and her family are also planning a celebration of life in Los Angeles for Kelley's friends and colleagues in the area.