The shooting happened at about 2:30 pm in the area of 26th and Hawthorne.
The little girl was taken to Mercy Hospital, where she died of her injuries.
Detectives say the gun was inside the home and was unsecured when the boy, who is related to the victim, got to it.
Police say the shooter, a boy related to her, got a hold of a handgun that was not secure and accidentally shot the victim.
The girl's father, 44-year-old Rodney Mathews, drove her to the hospital himself.
He was seen speeding away after leaving her there, and led police on a short pursuit.
When he pulled over, officers say he told them he was trying to get back to the other children at the home.
He has been arrested and booked on charges of child endangerment which resulted in the death of a child, felony reckless driving while evading officers, and a prohibited person in possession of firearms and ammunition.
Officers say this tragedy serves as an unfortunate reminder for firearm owners to secure their weapons and keep them out of reach from children.