Seo Min-woo, leader of K-Pop boy band 100%, died Sunday, March 25. He was 33 years old.

In a statement provided by his record label, TOP Media, Seo Min-woo (often referred to as just “Minwoo”) passed after suffering cardiac arrest in his home in Gangnam, Seoul, South Korea. It reads—translation from Billboard—“His family, the 100% members, and the TOP Media artists and staff members are all grief-stricken and in mourning from the unexpected, sad news.”

Seo Min-woo was the leader of the five-member K-Pop boy band 100% since their formation in 2012. The group released five EPs, beginning with We, 100%, in September 2012. Seo’s last contribution to the band was their Japanese EP Song For You, released on Valentine’s Day of this year. As Billboard reports, Seo also pursued acting outside of his music career and last year appeared on the Korean television reality series, The Unit, where former K-Pop stars fight for a second chance at fame.

100% has two concerts scheduled in Japan late next month, April 21 and 30. TOP Media has yet to announce if they will cancel the dates.

We will continue to update this story as more information becomes available.