Australian metalcore band Polaris has confirmed the death of guitarist Ryan Siew at age 26.

In an emotional post shared Tuesday on Polaris’ Instagram page, band members Daniel Furnari, Jamie Hails, Rick Schneider and Jake Steinhauser shared that Siew died June 19.

“For 10 incredible years he was our best friend and artistic soulmate,” the musicians wrote. “Those years will never be enough.”

They went on to note, “Ryan, we will love and miss you for the rest of our days, and we will never fill the hole that you leave in all of our lives. Our hearts are with his family first and foremost, but also with all those whose lives he touched.”

A cause of death was not revealed.

Siew, who was born in Sydney, Australia, joined Polaris in 2013 when he was just 15. The band released its first studio album, “The Mortal Coil,” about four years later. The record received widespread critical acclaim and nabbed Polaris its first nomination for an ARIA Award, Australia’s equivalent of a Grammy.

Earlier this year, Siew expressed concerns over both his mental and physical health on social media.

“I’ve had to step away and spend most of 2023 working on myself and for the first time for as long as I can remember, I’m happy to say I’m no longer on any anti depressants, no longer living with the constant brain fog and lethargy,” he wrote on Instagram on Jan. 26. “Although I’ve also had a few health scares that have been quite sobering.”

He went on to note: “Between all of that, I think I’m back on track to be the best version of myself. I’m learning new things, growing and I’m most importantly recovering.”

Earlier this month, Polaris announced that Siew would not be joining the band at Rock for People, an annual music festival in the Czech Republic, “as he is taking some time off the road to deal with some ongoing health issues.” Last week, the group canceled all of its remaining European tour dates due to “a serious personal crisis in our family.”

Polaris’ third album, “Fatalism,” is set for a Sept.1 release. At present, the band is slated to kick off a U.S. tour this fall in Los Angeles.