The shooting happened at 1:30 a.m. in the 7800 block of South Cornell Avenue, police said. The women, 48 and 50, were on a porch with a group when they heard gunshots and felt pain, police said.
The attacker is said to be between 19 and 23. Police said the man approached the girl as she walked east on 93rd Street at Cornell Avenue, made small talk for several minutes, then pulled out a handgun and forced her into an alley near 93rd Street and East End Avenue, where the attack occurred.
The boy suffered life-threatening burns on much of his body; including his head, face, and chest.
Chicago Police have issued a community alert following three similar strong-arm robberies in South Shore, near the southern end of Jackson Park.
One man is dead, and another is fighting for his life this morning, after separate shootings in the South Shore and Woodlawn neighborhoods.