CHICAGO (STMW) — A 17-year-old boy was shot and critically wounded in a Greater Grand Crossing neighborhood armed robbery Tuesday night on the South Side.

The teenager was standing in an alley about 9:20 p.m. in the 6700 block of South Prairie Avenue when an unknown male approached from behind and announced a robbery, police said.

The boy was then shot in both legs, causing him to fall to the ground, police said. Once the boy was on the ground, the robber stole $500 from his pockets, then fled on foot.

The teenager was taken in critical condition to John H. Stroger Jr. Hospital of Cook County, police said.

No one is in custody as Area Central detectives investigate.

(Source: Sun-Times Media Wire © Chicago Sun-Times 2014. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed.)