An autopsy found Joyner-Francis, who had a heart condition, died of sudden cardiac death, aggravated by physical and emotional stress from the fight.
All three girls, including a 17-year-old charged with criminally negligent homicide, are being tried as juveniles. If adjudicated delinquent, the 17-year-old would be subject to supervision until age 19.
The two other girls are charged with conspiracy for allegedly helping plan the fight.
The Associated Press is not naming them because they are juveniles.