Michelle Jones, 17, is charged with armed robbery with a firearm, and attempted armed robbery with a firearm, in the mugging of two University of Chicago students on Oct. 16, 2012. (Credit: Chicago Police)

Updated 10/18/12 – 12:32 p.m.

CHICAGO (CBS) — Four teenage girls have been charged with robbing two University of Chicago students at gunpoint.

Police said two of the girls approached a 28-year-old woman and a 22-year-old man as they were walking in the 5600 block of South Blackstone Avenue, shortly after midnight on Tuesday.

A 14-year-old girl allegedly displayed a handgun, while a 15-year-old girl demanded the victims’ backpacks. The man handed over his backpack, but the woman did not, and the 14-year-old allegedly pistol-whipped her. As she was hitting the woman, the gun went off, but no one was struck by the bullet, police said.

The robbers fled the scene, but were captured a short time later. A University of Chicago police officer found two of the suspects after a security guard reported seeing two suspicious females run by a building at 49th Street and Lake Park Avenue. After the two girls were arrested, the victims later identified them as the robbers.

Another suspect was found after police on patrol spotted a car going the wrong way at 48th street and Dorchester Avenue. The car crashed when the officers tried to stop it. A 16-year-old girl inside ran away, but was caught, and later admitted to being the getaway driver.

The fourth suspect, a 17-year-old girl, was arrested in south suburban Calumet Park, around 2:45 a.m. It was not immediately clear what her role was in the robbery.

Three of the girls are being charged as adults.

Michelle Jones, 17, of the 12200 block of South Elizabeth Street; Nataya Collins, 16, of 1200 block of West 74th Place; and Kenyadrea Simpson, 15, of the 500 block of West 125th Place each were charged with armed robbery.

Bond was set yesterday at $100,000 for each of the three charged as adults.

The 14-year-old girl was being charged as a juvenile.