Their bodies were discovered in their home in the 5300 block of South Winchester on the city's South Side.
The emotional relatives of Chavonne Brown drove away after gathering outside the mother's South Side home just hours after she and one of her sons are murdered.
"It's a tragedy," said relative Otis Brown. "A 5-year-old baby shot in his sleep. What kind of animal would do something like that?"
The 31-year-old and her son, Sterling Sims, were found shot to death inside a home in the city's Back of Yards neighborhood.
Brown moved into the first-floor unit with her boyfriend a few months ago, after living with the mother.
"One of my kids had just come in. I was fussing at him then I hear the gunshots," said neighbor Veronica Smith. "They sit on the floor. I come out. The police are here telling me they had been shot in the house."
Authorities were alerted about the attack around 2:40 Friday morning when friends say the woman's other son, an 11-year-old who witnessed the slayings, called police.
Relatives say the older child was unharmed because the gunman's weapon jammed.
Investigators would not confirm that, but say there's no evidence of a break-in and don't believe the crime is random.
Some remain baffled as to who would commit such violence.
"She kept to herself you know," said neighbor Mike Donaldson.
Friends say Brown was a babysitter and a dedicated mother.
Sterling had just finished preschool two weeks ago.
"She was their everything. Her mother helped her out but, oh my god," said Cindy Griffin, the victim's godmother.
Meanwhile, area residents remain concerned.
"I just hope there is no retaliation, that the police do their job find out who did it because we don't need continued bloodshed," said neighborhood resident Keith Kysel.