The music world and fans alike were stunned by the sudden passing of legendary singer Prince earlier today, but what is even more shocking is what has been rumored to be his cause of death.

What exactly did kill the 57-year-old "Purple Rain" singer has not been officially revealed as of yet, but it is believed that the flu is what managed to kill the musical legend.

Prince was ill the past few weeks, his rep told E! News, after he canceled two shows at the beginning of the month, though he did still perform in Atlanta after a week's rest.

"He started not feeling well and expressed that to a few close friends," a source told the website. "He never spoke about what the illness was only that he is just was fighting a cold and he would get better and not to worry. He never liked to complain."

He was also treated at a hospital in Illinois in April 15, after his jet was forced to make an emergency landing on his way home to Minneapolis. Again, he claimed to be fine, until his health reportedly took a turn for the worse earlier this week.

"He was supposed to meet up with a few people for dinner a few days ago, he decided to cancel because he was still not feeling well and he needed to reschedule," the source said.

As shocking as it seems, the flu actually could have been what killed the icon. According to the CDC, the flu can result in death for those who are at high risk from flu-related complications. Those who are usually considered at high risk of complications include children younger than five, adults age 65 and over, and pregnant women. However, people with conditions including asthma and other respiratory infections and disorders, heart disease, kidney and liver diseases and other conditions can also be at high risk as well.

Though Prince did not traditionally fit into any of the categories that would have likely tagged him as high-risk, his religion as a Jehovah's Witness could also have played into the treatment he chose to receive. Though members of the religion try to take extremely good care of their bodies, they do occasionally see doctors when needed, unless a procedure conflicts with Bible principles, which prevents them from procedures including blood transfusions.

A medical examiner is expected to release the true cause of death later this week.