Police say they believe alcohol played a role.
The accident happened shortly before 2 p.m. Friday in the 500-block of West 111th Street in the Roseland neighborhood.
A car crashed into a pole, killing Lavashia Penn, 34, and her 13-year-old son, Damari McCaster. Both were passengers in the car.
The boy's father, Kevin McCaster, says the group was attending his mother's funeral.
"I lost my son, and they came from my mama's funeral. They were trying to show respect to my mama, and they lost their lives, too," Kevin McCaster said.
Two others were injured, including the driver, 32-year-old Nancy Spencer. She is charged with one count of misdemeanor DUI.