Tragedy struck, as Swedish DJ and musician Avicii has died.
His real name waws Tim Bergling.
He was only 28 years old.
His fans, who are beyond numbering and live all over the world, are in mourning at this sudden, unexpected loss.
Those who knew him best -- his friends and those who worked with him, particularly within the field of music, are expressing their shock and sorrow.
Taking to Twitter, they are remembering their late friend and colleague and expressing their heartwrenching grief.
These are their tweets:
Liam Payne is of course world-famous as a member of One Direction.
Calvin Harris is a DJ, an underwear model, and is best known for being Taylor Swift's ex-boyfriend.
Ruby Rose clearly knew Avicii personally. She is best known for roles on shows like Orange Is The New Black and Dark Matter, and will appear in the upcoming film, The Meg.
Joal Thomas Zimmerman is best known by his stage name, deadmau5. The "5" numeral is pronounced like the letter "S." He is a producer, DJ. musician, and composer. He does a lot with house music and with EDM.
Justin David Blau is better known by his stage name, 3LAU, is a DJ and EDM producer.
Kevin McHale is formerly of the boy band known as MLT, he is best known for having played Artie on Glee.
DJ Pauly D
Paul DelVecchio of course rocketed to fame on Jersey Shore. He remains a television personality, but is now a DJ.
Christopher Comstock is known in the music world by his professional name, Marshmello. He is an American EDM producer and DJ. Famously, he worked with Selena Gomez on "Wolves."
American Authors are a rock band based in New York. At the moment, they are signed to Island Records.
Charles Otto Puth Jr. is a singer, songwriter, and record producer. He climbed to fame through YouTube.
Known (and sometimes roasted) for his method acting, Jared Leto is also a singer, songwriter, and director.
William Sami Etienne Grigahcine is a French DJ who hails from Paris. Known professionally as DJ Snake, he works as a record producer.
Artem Stoliarov is known professionally as Arty. He is a Russian trance/progressive house music producer. He is also a DJ and model.
Dua Lipa is a singer, songwriter, and model whose career in music began when she was only 14. Like so many young stars, she rose to fame after performing covers on YouTube.
Matthew Russell is one third of the DJ trio known as Cheat Codes.
LOU's tweets about enthusiasm for Coachella have been tempered. It is worth noting that LOU's latest single is titled "Will Never Forget You."
Nile Rodgers Tweeted His Disbelief
Some people couldn't believe what they were reading when they learned the heartbreaking news.
Nile Rodgers Tweeted Again
Nile Gregory Rodgers Jr. is a record producer, arranger, guitarist, songwriter, composer, and musician.
Sabrina Carpenter is an American singer, songwriter, and actress. She is most often recognized for her role on Girl Meets World.
Best known for their shoutout in Miley Cyrus' "Can't Be Tamed," Rock Mafia is an American record production and songwriting team that consists of Tim James and Antonina Armato.
Annie Lööf is a Swedish politician. You don't have to be in the music business to mourn a musician when he dies.
Paris Blohm is a DJ based in Los Angeles.
Throttle is best known for EDM songs like Hit The Road Jack and Baddest Behavior. He is managed by ICONS.
Spencer Brown's most recognized EDM work includes songs like "Will I Ever Find Love" and "Tassajara." Like so many others, he had toured with Avicii.
Madison Beer is a singer and actress who rose to stardom thanks to a social media boost by Justin Bieber.