In addition to their mother, a 65-year-old friend of the family and the woman whose Toyota 4runner had been hijacked were also injured. Investigators said the carjackers forced her into the back seat as they took off.
The carjackers abandoned the Toyota after the crash and ran off. No arrests had been made late Friday afternoon.
Clark said a reward of $60,000 was being offered.
The mother had set up a small fruit stand on Allegheny Avenue to raise money for the family's church, police said.
Police said the carjacking occurred about a mile from the crash scene. The driver apparently lost control of the Toyota as he made a turn and ended up hitting a tree after veering into the fruit stand.