In each robbery, the group of about five to eight teens has gone up to the woman or teen and hit her in the head, police said in an alert issued Friday. Victims have also been kicked.
The robbers have stolen cellphones and backpacks containing tablets, then fled on foot.
The recent robberies took place:
• On Sunday at 9 p.m. in the 100 block of North Michigan Avenue.
• On Sunday just after 9:10 p.m. in the 200 block of East Randolph Street.
• And on Wednesday at 10 p.m. in the first block of East Van Buren Street, just east of State Street.
Police did not release a detailed description of the Negro attackers, who they said include male and female teens.
Anyone with information is asked to call Area Central detectives at 312-747-8384.