State police are attempting to inform each victim's family, which is why the victims' names have yet to be released.
Apparently, the victims were on their way to a temporary work assignment when something went wrong.
The backup on the Eisenhower lasted for hours during Thursday morning's commute. All westbound traffic was detoured at Route 83 after the fatal accident around 6 a.m.
A silver Explorer with eight people inside ended up in a ditch around Addison Road.
"The vehicle rolled over to the right in the ditch, rolled over apparently several times," said Lt. Brian Windle, Illinois State Police.
Three women were ejected. They and another female passenger were killed. Three male passengers and the driver survived.
State police say only the driver and a passenger in the front seat were wearing seatbelts and that the vehicle was traveling above the speed limit.
"Definitely speed and lack of seatbelt use is probably what caused the fatalities because the people were ejected from the vehicle, and from preliminary evidence, they did not have seatbelts on," Windle said.
The driver, Margot Santillan, 31, was charged with improper lane usage, failure to reduce speed, no valid driver's license, no insurance and for driving with suspended registration for no insurance.
Santillan was giving the other seven a ride to work. They met at a Chicago staffing agency early Thursday morning and Santillan was taking them to a job in the western suburbs.
Santillan was released from a west suburban hospital, but her Chicago neighbors say they have not seen her since.
State police are asking anyone who may have seen anything on I-290 around 6 a.m. Thursday to call the Illinois State Police Elgin office at 847.931.2405, ext. 205.