The infant was found when police were called to an apartment Thursday around 8 p.m. on East 69th Street and South Cornell Avenue.
It is not known how the burns and bruises occurred, but fire officials say there were no reported fires in the area Thursday night.
The child welfare agency says no prior reports have been filed regarding the family, and there are no other children in the home.
The baby suffered burns to his face and chest and bruises to his head.
Neighbors say they never heard anything out of the ordinary coming from the child's apartment.
"I just hear the footsteps of the baby running back and forth," said Rosemary Carter, who lives in the apartment below the victim's family.
Carter said she saw the boy periodically with his mother and a man who may have been the mother's boyfriend. She says they moved in recently and she didn't know them well.
Neither did fellow neighbor Tasha until she heard a knock on her door Thursday night. It was the boy's mother asking if she could use the phone to call 911.
"That something was wrong with her baby and that they needed to hurry up and get here quickly," said Tasha, who lives in the apartment above the victim's family.
One neighbor suspects if there was foul play, few would speak up about it.
"Nobody wants to say anything. And as long as no one doesn't say anything, things are going to keep happening," said Lakedia Prentiss, who lives around the corner.
The Department of Children and Family Services says it has had no prior contact with the family.
The Sun-Times Media Wire contributed to this report.