SEOUL - Kim Dong-yoon, the main rapper of K-pop group Spectrum, died on Friday (July 27), shocking his fans both at home and abroad.

An autopsy has been ordered by the authorities, The Korea Herald reported.

The 20-year-old had been active on social media up until the day before his death.

Not only did he post pictures on the group's Instagram account but he also initiated a livestream broadcast to interact with fans.

Spectrum's agency Wynn Entertainment said: "Spectrum member Kim Dong-yoon left our side. It was so sudden that his family, his fellow members and all our employees are still in mourning.

"We are so sorry and our hearts hurt to have to pass along this sad news to the dedicated fans who have loved as well as supported Dong-yoon thus far."

Kim's family plans on having a quiet ceremony in his honour when the time is right.

Spectrum debuted in May this year with the album Be Born.

Kim was a popular contestant on Mixnine, a reality show hosted by YG Entertainment.