It happened just before 3 p.m. Thursday. Witnesses say it was a horrific collision and it was raining very hard at the time.
A cab driver was the first person on the scene to help the victims and rushed the children to the hospital.
Witnesses say that the car was headed north on South Shore Drive. The grandfather and his two grandsons were crossing South Shore Drive from the lake to the neighborhood when the car hit them at full speed, sending them flying into the air.
"I seen a gentleman with some kids running across the intersection. And he was, like, in the middle of the street. And the car just impacted the gentleman and the two babies just flew," said witness Kim Lenoir. She said it did not appear that the driver tried to stop.
Five-year-old Ashton Barker was pronounced dead at Comer Children's Hospital. His 9-year-old brother, Savion Smith, is in stable condition at Comer. The boys' grandfather, Jesse Barker, is listed in stable condition. He underwent surgery at Northwestern Hospital.
"This is unforgivable and it is a tragic loss for my family," siad Christopher Barker, boys' uncle and Jesse Barker's son. He is a teacher at Betsy Ross Elementary where Ashton just graduated from kindergarten.
Police are looking for a 2005 Ford Taurus, white or cream colored, with windshield or front-end damage.
"I don't get a chance to say goodbye to my nephew or see the important things in his life, and that was not how I expected his life to be," said Christopher Barker.
Police say they have several leads on the driver, but no one is in custody.