Police said she was inside her East Chicago home's living room when the stray bullet came through a window. She was not in the intended target, police said.
She remained hospitalized in critical condition Friday.
The shooting happened in the 4500-block of Magoun Street in Northwest Indiana at about 10 p.m. Thursday.
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Police said around that time they received an alert about gunfire in the area from their ShotSpotter system.
Just moments after officers arrived to find that 16 rounds had been fired, there were calls for help about a child being shot.
Paramedics stabilized the girl who was eventually airlifted in critical condition to the University of Chicago Comer Children's Hospital.
While investigators confirmed an older male relative of the girl was shot last week, they still do not know if the attacks are connected.
"A little over a week ago we did have a shooting that had something to do with a person in this house, but again we're not sure it's related," Deputy Chief Jose Rivera with the East Chicago Police Department.
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Neighbors said they were told the family moved to usually quiet town from Chicago to escape neighborhood gang and gun violence.
Meanwhile, investigators returned to the neighborhood to gather more evidence and are hoping the security cameras at a nearby school caught the shooters as they fled the scene in a getaway car.
Law enforcement officials are trying to find video footage of the incident.
"We're going to check with the school and city right down the street. They have a camera system to check and see who actually fled from this area," Rivera said.
There have recently been several incidents, possibly sparked by gang violence, on the same block, Rivera said.
No arrests had been made in connection with the incident as of late Friday morning.
Anyone with information on the shooting is encouraged to call the East Chicago Police Department's anonymous tip line at 219-391-8500.