Associated Press

DOVER, Del. — Three teenage girls have been charged in a high school restroom assault in Delaware that left a 16-year-old girl dead, authorities said Monday.

The Delaware attorney general's office announced the charges after meeting earlier in the day with the mother and older brother of the victim, Amy Joyner-Francis.

Joyner-Francis, a sophomore at Wilmington's Howard High School of Technology, died April 21 after a fight broke out shortly before classes were to begin.

Authorities said a 16-year-old girl, the only person believed to have struck Joyner-Francis, is charged with criminally negligent homicide, which is punishable by up to eight years in prison. Prosecutors said they will seek permission from Family Court to have the girl tried as an adult in state Superior Court.

The other two suspects, also 16, are charged with third-degree criminal conspiracy, which is punishable by up to a year in prison, they added. They will be tried in Family Court.

The Associated Press is not naming any of the suspects because they are juveniles.

Authorities noted that while the evidence indicates that all three suspects were involved in planning a confrontation with Joyner-Francis, only one actually hit her. Authorities did not disclose a motive for the confrontation.

"The individuals responsible for Amy Joyner-Francis's death are minors, but they must be held accountable for their actions," the state Department of Justice said in a statement.

Authorities disclosed Monday that Joyner-Francis died of sudden cardiac death, with a contributing factor of physical and emotional stress because of the physical assault. An autopsy did not detect any internal injuries or significant blunt force injuries.