Three of the robberies were committed in the late afternoon on Oct. 22, and one was committed Saturday, Oct. 29, in front of a downtown senior citizens complex.
The victims in all four cases were physically assaulted by the three suspects before and after their purses and backpacks were stolen, police said.
During each robbery, the suspects drove up to or past the victim in a light gray or silver four-door sedan. The suspects would then jump out, assault and rob the victim, and get back in the car, according to police.
A surveillance camera caught captured the Oct. 22 robbery.
The suspects were described as three black women between 17 and 19 years old.
The suspect vehicle was driven by a black male and is believed to be a four-door 1985 to 1990 Volvo 740 series with damage to the right side of the car, police said.
Anyone with information about the robberies is asked to call (800) 488-9383 to leave an anonymous tip or speak with Detective Mark Nicol. Nicol can also be reached by email at firstname.lastname@example.org