Brad Arnold, founding member and lead singer of 3 Doors Down, has died. He was 47.

“With heavy hearts, we share the news that Brad Arnold, founder, lead singer, and songwriter of 3 Doors Down, passed away on Saturday, February 7th, at the age of 47,” the band wrote in an Instagram post.

Arnold died of kidney cancer.

“With his beloved wife Jennifer and his family by his side, he passed away peacefully, surrounded by loved ones, in his sleep after his courageous battle with cancer,” the post continued.

The singer was known for radio hits including “Kryptonite,” “Here Without You” and “When I’m Gone.” The band said Arnold wrote “Kryptonite” while in his high school algebra class.