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In a statement to TMZ, Posey's family said, "Although she was an accomplished teenager with a bright future ahead of her, unfortunately in one impetuous moment, she made the rash decision to end her earthly life."
Washington State Patrol confirmed to Fox News Digital that they are conducting a death investigation involving a minor at Birch Bay State Park. Authorities would not confirm that it is related to Posey's death.
The family went on to tell TMZ they are devastated by her death and praised her many accomplishments during her life, saying, "She won countless crowns & trophies after competing on the pageant circuit her entire life ... Her highly acclaimed talent as a contortionist had already led to professional touring job offers, and she had recently been selected to be a cheerleader at her high school next fall."
Her family said she had plans to continue working in the entertainment industry and also dreamed of becoming a commercial pilot.
Per the outlet, the family has also set up a Whatcom Community Foundation fund in Posey’s name in hopes of getting "much needed resources to students in crisis."
Her mother, Marcy Posey Gatterman, announced her death on Monday with a Facebook post.
"I don’t have words or any thoughts," she wrote. "A beautiful baby girl is gone. Please give us privacy as we mourn the loss of Kailia. My baby forever."
Posey got her start on "Toddlers and Tiaras," the same TLC show that launched the career of Alana "Honey Boo Boo" Thompson. The TLC show ran for seven seasons and ended in 2013. The show followed families as their young children competed in beauty pageants.
Kailia continued to participate in pageants following her time on the show and had recently competed in the Miss Washington Teen USA pageant in February.
"I’m going to be competing in Miss Washington teen USA in February and I am so excited!" she wrote on Instagram.
Following the pageant, Kailia shared photos of herself and captioned the post, "One word. Thankful."
A rep for Discovery, which owns TLC, did not immediately respond to Fox News' request for comment.
Fox News' Lauryn Overhultz contributed to this report.