It happened after 3 a.m. Wednesday at home on Bloyd Street near East Woodlawn Street.
Officers arrived to find the 14-year-old victim with gunshot wounds to the hand and chest.
She was rushed to an area hospital in critical but stable condition.
Investigators soon determined a group of teens at the home were playing with the weapon when one of the teens fired it once, hitting the girl.
Firefighters were called to help police search for the weapon.
Action News is told they found a rifle and a handgun on the roof of the home.
Police believe the person who fired the weapon is an acquaintance of the victim and say the shooting appears to have been accidental.
A 17-year-old surrendered to police Wednesday night, but has not been charged.
It is the second accidental shooting involving teenagers in Germantown in as many weeks.
Exactly one week ago, on June 29th, 13-year-old Chris Mackey died after a gun found by a group of teenagers at a home on East Walnut Street went off.
A 15-year-old and 17-year-old have been charged in connection with that case.