Police responded to a battery-in-progress on the 1700-block of North Neva Saturday night around 11 o'clock.
Officers found 18-year-old Nakella Harper pinned under a vehicle about a block away. She was pronounced dead at the scene.
Police say the teenage driver of the vehicle did stop. They were questioning her.
The mother of the graduate said as the guests were leaving the party, there was some type of argument in the street. Harper was apparently trying to get into a friend's car when she was somehow struck by that car and was dragged.
"She was a loved person. She had so many friends," said Carmen Harper, the victim's mother. "She loved to dance. She loved to do hair."
"I'm really sorry because, you know, it happened after my son's graduation party. So, I can't even, there's no word to even express how I feel," said Sylvia Williams, mother of graduate.
Family members say Harper was to start classes at a community college on Monday. They also say Harper was on the cheerleading, track and swimming teams at Proviso West High School in Hillside.
So far, no charges have been filed.
(The Associated Press contributed to this report.)