Lt. Bill Guiberson of the Chubbuck Police Department says emergency workers responded to a Chubbuck home at about 3 p.m. Wednesday and took the victim to Portneuf Medical Center in Pocatello. The hospital confirmed later in the evening the girl had died.
In a statement Thursday, police said adults were in the home at the time of the shooting but were in a different room.
It's unclear whether the victim lived at the residence; the statement said only that she was there "visiting with friends" when the shooting happened. Police didn't return a call Thursday from The Associated Press.
Investigators have not released the type of gun involved or said how the children got access to it.
No names or other details have been released, and police continue to investigate.