The woman, who is in her 50s, was walking near South Columbian Way and 24th Place South just after 10:30 a.m. when four male teenagers approached her.
Police say one of the teens pointed a handgun at the woman and took her purse before all four took off on foot down a nearby alley. The woman was not injured.
Officers arrived on scene moments later. They searched the area but didn't find the robbers.
The robbers are described as black males in their late teens to early 20s. Three of them wore all black and one wore black pants and a black and white checkered top. The suspect with the black and white checkered top brandished the handgun, according to police.
Anyone with information about the robbers is asked to call the police.