Three girls were charged in Delaware on Monday in the death of a 16-year-old high school sophomore who was attacked last month in a school bathroom in Wilmington.

Amy Joyner-Francis was assaulted April 21 in the main-floor girls' bathroom at Howard High School of Technology. She died later that morning at A.I. du Pont Hospital for Children.

Trinity Carr, 16, was charged with criminally negligent homicide, which is punishable by a maximum of eight years in prison. Prosecutors will request that she be tried as an adult.

Zion Snow, 16, and Chakeira Wright, also 16, were charged as juveniles with third-degree criminal conspiracy. They face a maximum one year in prison.

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

The Justice Department said Joyner-Francis's cause of death was from a cardiac incident from a preexisting heart condition - large atrial septal defect - with a contributing factor of physical and emotional stress due to physical assault.

"The cardiac incident would not have occurred if she had not been assaulted," the department said.

The three girls were involved in the planning of the confrontation with Joyner-Francis, but only Carr actually hit her, the department said, explaining the differing charges.

The attack reportedly was over a boy.