(CNN)As stunned fans mourned legendary singer Prince, questions remained on what killed him days after he performed in Atlanta to rave reviews.

Authorities are investigating the circumstances surrounding his death. An autopsy will be conducted Friday, starting at 9 a.m. CT (10 a.m. ET).
Prince Rogers Nelson, 57, died Thursday after he was found unresponsive in an elevator at his studios in Chanhassen, Minnesota.
Paramedics tried to perform CPR but were unable to revive him, authorities said. He was pronounced dead at 10:07 a.m., less than 30 minutes after sheriff’s deputies responded to a medical call at the scene.