Witnesses told police that a car was traveling at high speed when the driver lost control and crashed into a pole.
Killed were Norma Montesinos, 29; Gabriella Sanchez, 19; and Cecilia Gentil, 25, all from Chicago. One male victim still has yet to be identified.
Montesinos, Gentil and the male victim who died were ejected from the car and pronounced dead at the scene.
Three more occupants of the car were taken to area hospitals in critical condition. Sanchez died at Mt. Sinai Hospital. A 23-year-old man was also transported to Mt. Sinai and was reportedly in "very critical" condition Saturday morning.
Another male victim was transported to Stroger Hospital in critical condition.
The crash happened at approximately 12:30 a.m.
Chicago police said early Saturday that the accident was under investigation, and they could not confirm what caused the driver to lose control of the car.