CHICAGO (CBS) — Four women were injured Monday morning, when a car crashed on the Ontario feeder ramp to the Kennedy Expressway, throwing two of the women from the car.

Illinois State Police said the car was headed west on the Ontario Street ramp to the Kennedy Expressway, near Halsted Street, when it crashed shortly after 1 a.m.

Two women were ejected from the vehicle. A total of four women were taken to Northwestern Memorial Hospital. Three of them were in critical condition, and the fourth woman’s condition was described only as “stable.”

The crash caused a major backup on the Ontario feeder ramp, but it reopened by 4 a.m.

The cause of the crash was under investigation.