(CNN) — American climber Balin Miller has died at the age of 23 while climbing at Yosemite National Park , his mother confirmed on Thursday.

Miller was attempting to summit El Capitan, Yosemite’s iconic wall soaring 3,000 feet from the valley floor, via the “Sea of Dreams” route when the accident occurred, Jeanine Moorman – Miller’s mother – wrote in a blog post on the VIRR website , the family’s outdoor goods business.

“This is unthinkable,” Moorman wrote in tribute to her son. “At this time, we do not yet know all the details. What we do know is that the world has lost an extraordinary soul, and our hearts are shattered.”

Moorman went on to describe her son as having “a touch of Robin Williams’ wild energy. Strategic, curious, and endlessly playful, he brought light where

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