Jonghyun, the lead singer of K-pop band Shinee, died Monday, SM Entertainment said in a statement. He was 27.

“We are sorry to be the bringer of such tragic, heart-breaking news,” said the entertainment company, home to Jonghyun’s South Korean boy band Shinee, according to Koreaboo. “On December 18th, SHINee’s Jonghyun left us very suddenly.”

The Associated Press reported on Monday that Jonghyun’s sister told police that the singer sent her text messages reading “Final farewell” and “I’ve had difficulties” prior to the discovery of his body, though authorities have not yet determined a cause of death. SM asked the media to “please refrain from reporting on rumors and guesswork so the family of the deceased can honor him in peace.”

According to the statement, the pop star (real name Kim Jong-hyun) was pronounced dead at a hospital after he was found unconscious at a residence in the Cheongdam-dong area of Seoul, South Korea.

“Our sadness cannot compare to the pain of his family, who had to say goodbye to a son and a brother,” said SM. “But we have spent a long time with him, and SHINee members and SM Entertainment staff are all in deep mourning and shock.”

Following his success leading Shinee, the singer-songwriter pursued a solo career in 2015. His label said he “loved music more than anybody else and he was an artist who did the best to perform his absolute best on stage,” adding, “It breaks out heart to have to bring this news to fans who loved Jonghyun so much.”

A funeral will be “held quietly with his relatives and company colleagues,” said SM.