Jasmine Martinez was found passed out after riding the Revolution roller coaster at the amusement park on Friday and died a day later.
The coroner said Tuesday that Martinez died of natural causes and not from an accident. However, there were no further details on the girl's health condition.
Her family has yet to release any statements regarding her death.
The girl was found unconscious after riding the Revolution roller coaster at the amusement park on Friday.
Firefighters were called to the park shortly after 4 p.m. and said the girl was airlifted to the hospital.
Six Flags released a statement, extending condolences to the girls' family and friends.
We are deeply saddened to learn of the death of Jasmine Martinez. Our thoughts and prayers are with her family. http://t.co/JtEYWS7WVe— Six Flags MM (@SFMagicMountain) June 15, 2015
Also in the statement, park officials said more than 45 million guests have safely ridden the Revolution roller coaster since it opened in 1976.