Chicago police say they do not believe Porshe Foster was the intended target.
According to police, the girl was staying with a friend Monday night in the Marquette Park neighborhood. At approximately 9 p.m., they walked over to a house near 70th and Campbell. As they were talking to several friends, Chicago police say a man walked up and opened fire on the group in a backyard.
Keith Terrell lives near the crime scene and can point to the bullet holes left in his door. He described how Foster collapsed inside his stairwell after being shot.
"I felt her pulse. She had a pulse, and she was still breathing. So, I hurried up and called the ambulance. I said, 'This girl is losing her life right here. You should hurry up and come,'" said Terrell.
Foster was taken to an area hospital with a bullet wound to her back, but she died less than an hour later.
Bonita Foster, the girl's mother, talked to ABC7 Chicago about the future her daughter would never get to see.
"She was only 15. She didn't even get to live her life. She didn't get to graduate high school or go to prom. We had a little fund where we were saving money for her to go to prom. She didn't get to do any of that," the mother said.
"There needs to be an end to this foolishness. It has to stop. It has to stop somewhere. She didn't deserve it at all," Bonita Foster added.
A group of parents and community members organized a rally near the scene of the shooting Tuesday night at 6 p.m. Chicago police say the shooting appears to be gang-related.
Porshe Foster was a sophomore at Ace Technical Charter High School. She played basketball and volleyball and was the youngest of six children. Her father said she was an honor roll student.
Foster's sisters showed ABC7 the small unwrapped guitar they planned on giving her for Christmas. They said they were heartbroken she would never get to play it.
"You never think it would happen to you -- nobody close to you like this. I would never think something like this would happen to 'Shay.' She never did nothing to nobody," said sister Robyn Foster.
As the family asked for prayers, community activist Andrew Holmes passed out fliers hoping people would come forward with information.
"What we want them to do is quit fingerpointing at the Chicago Police Department and the city because these are somebody's kids killing somebody else's kids," Holmes said.
Chicago police said early Tuesday a red car was seen in the area before the shooting, but authorities have not said if that car is related to the shooting.