A family is reeling after an 11-year-old Antioch, Calif. girl suffering from a strep infection developed toxic shock and ultimately died, the Contra Costa Times reported Friday.

Emily Toy, who played the violin and liked the Jonas Brothers, came down with a mysterious infection in May. It was later determined to be group A streptococcus, which sent her body into toxic shock and shutdown her vital organs.

Emily was kept on life support for a month before dying June 22. Her parents, Wendy and Alan, told the newspaper that Emily first complained of a sore throat and neck after a softball tournament May 23. Two days later she developed a fever, but surprisingly two strep tests didn’t detect the infection before her body started shutting down.

Dr. Jake Sinclair, who oversees the pediatric referral clinic where Emily was treated, said the rapid strep test has a 97 percent sensitivity rating — and that it's impossible to say why it did not reveal the infection.

Strep toxic shock syndrome occurs when the bacteria, which causes strep throat, enters the blood stream causing a rapid drop in blood pressure and organ failure, according to the Centers for Disease Control and Prevention.

From 540 to 690 cases of strep toxic shock syndrome are reported in the United States each year — half of which are fatal.

"It's the pediatrician's nightmare," said Sinclair, who has seen a few cases of fatal strep over the course of his career.

Click here for more on this story and to see photos of Emily at ContraCostaTimes.com.