The crash occurred at about 6 a.m. in the 2600-block of West Madison Street. Alcohol was found in the Buick, Chicago police said.
The victims who died were inside a Buick Le Sabre, which was traveling westbound on Madison at a high rate of speed. The driver of the car, 27-year-old Bernard "Bee" Chatman, lost control and collided head on with the CTA bus, which was traveling eastbound on Madison.
The bus driver and three passengers on the No. 20 bus were among the injured. They sustained non-life-threatening injuries.
A family member identified two of the people who died as sisters Ashley Moore, 25, and Tycika Fairley, 22. Moore had three children. Fairley had two and was pregnant.
Chatman has a young daughter. The third victim was identified as Erica Williams, 23.
Witnesses said they ran to the scene after hearing a loud boom.
"I heard the tire skid and then I heard the impact. When I came outside, I just saw a bunch of the neighborhood people trying to open up the doors of the car but they couldn't get them open. The driver of the car was partially hanging out the window," said witness Jbria Demery.
"My neighbor went over and tried to pull the driver out, but the car was burning so bad and there was so much smoke he had to stop trying and then the fire department came and did what they did," said witness Malinda Demery.