An 18-year-old male, who was also in the vehicle, survived and remains hospitalized.
The fatal crash took place just after 3 a.m. Saturday in the 100-block of Camp McDonald Road, in Prospect Heights.
Police say they have identified all the teenagers involved but are not releasing names because they have been unable to notify all the families yet. Meanwhile, investigators say it does not appear the teenagers were victims of road rage or a chase of any kind. Instead, police say it appears they were joy riding at an excessive speed.
Rachel Rowe, 12, is among those left shaken by Saturday's fatal crash. "I didn't actually know what it was. I didn't think it was this bad," she said.
Most of the neighborhood was asleep when they heard a loud "boom." "Well, at first I thought it was just something that happened downstairs, like something fell, 'cause it was real loud, but it was actually this," said neighborhood resident Emma Carman.
Police say the one-car crash happened as two males and two females were traveling at a high speed in a 2002 Honda Accord, which authorities say was reported stolen out of neighboring Mount Prospect.
"You feel for the parents and for the families. It's terrible," said the owner of the stolen car Michael Scala.
Investigators say one of girls killed was behind the wheel of the car when she lost control.
"She was traveling at a high rate of speed down eastbound Camp McDonald Road from Elmhurst Road. She lost control of the vehicle, went over a mailbox, careened off one tree, then struck the middle of the second tree. The vehicle exploded. Then the victims were ejected from the vehicle," said Prospect Heights Police Commander Eric Lundt.
The careening car came to rest in Scott Nielsen's yard just a few feet from his front door. "Just lucky that the car didn't go in the house because it would have been one of my kids bedrooms," he said.
Authorities say all the victims live in the area, and they range in age from 15 to 18 years old, possibly attending local high schools, including Prospect High School in Mount Prospect. The tragedy has neighborhood residents in shocked.
"There's a whole lot of kids, the schools right down the street, police department, fire department. So, everything's pretty calm around here," said neighborhood resident Ashley Dallas.
Authorities say that toxicology tests should tell them if alcohol or drugs played a role in this crash.