A court document says Mackenna Kronenberger was inside the bedroom of her home in Dayton, Ohio, when she was killed early on Wednesday.
Jason Tidwell and Dylan Angel, both 18, have been charged with murder.
The argument is said to have started on Facebook Messenger and both the men allegedly agreed to fight outside Tidwell’s home.
Witnesses told police they fought and Tidwell then got a gun from inside his home and began firing at Angel.
He took a gun from his car and fired several rounds towards Tidwell’s home, it was claimed.
Most of the bullets went into the house and at least one struck the girl, according to police documents.
Angel and Tidwell appeared in Dayton Municipal Court on Friday and are next due in court on 14 July.