In one case, the suspect approached someone who was waiting in line for food, displayed a gun and said "you know what time it is," according to Chicago police.
In the two other cases, the suspects entered a person’s vehicle, displayed a gun and demanded property before fleeing in a Lincoln sedan, police said.
One robbery happened at 1 a.m. Jan. 17 in the 7900 block of South Vincennes Avenue, police said. Two others happened in the same block on Jan. 21.
The suspects were described as two males between 25 and 30 years old and standing 5-foot-11 to 6-foot-3. They were wearing all black clothing.
Anyone with information is asked to call Area Two detectives at 312-747-8274.