The crash occurred at about 11:50 p.m. in the 4700-block of South State Street.
Police said a 28-year-old man driving a gray sedan was traveling east on 47th Street when he lost control and hit a fire hydrant.
Two passengers, a 25-year-old man and a 22-year-old woman, were both ejected from the car and pronounced dead at the scene, police said.
A third passenger, a 21-year-old woman, was transported to the University of Chicago Medical Center, where she was listed in critical condition, police said.
A fourth passenger, a 26-year-old man, was transported to Stroger Hospital, where he was listed in fair condition, police said.
A fifth passenger, a 23-year-old woman, was transported to the University of Chicago Medical Center, where she was listed in good condition, police said.
A sixth passenger, a 17-year-old girl, was treated at the scene, police said.
The driver of the car was not injured and was taken into custody, with charges pending, police said.