UPDATED 09/13/11 7:24 a.m.

CHICAGO (CBS) — Police are searching for the gunman who opened fire on three teenagers in the Rogers Park neighborhood and left them all wounded – including a boy who was only 13.

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As CBS 2’s Susanna Song reports, the youngest victim was in serious condition Tuesday morning. He was shot in the chest, and is now improving at Children’s Memorial Hospital.

The boy was initially hospitalized in critical condition.

He was shot, along with two other teens – a 15-year-old boy and a 19-year-old man – as they stood on the corner of Pratt and Ashland boulevards around 7:30 p.m. Monday. A male suspect approached the group and fired shots, then took off, police said.

It is unclear what the motive was, or who was supposed to be the intended target.

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The 15-year-old boy suffered a graze wound to the arm and was in stable condition at Children’s Memorial, police said. The 19-year-old man was also shot in the arm, and was taken to the St. Francis Hospital in Evanston, where his condition has stabilized.

At the site of the shooting, both Pratt and Ashland are major thoroughfares lined mostly with multi-unit apartment buildings. Far from being an isolated spot, traffic at the intersection is regularly heavy, since Ashland Boulevard jogs a slight distance to the east heading north from Pratt.

A woman walking to work Tuesday morning told CBS 2 the area around Pratt and Ashland has gotten progressively worse over the past couple of years.

At the scene following the shooting, crime scene tape was strung in front of a strip mall on the northwest corner of Pratt and Ashland, which includes the Pratt Cleaners, Jerry Mini Mart and the Living Water Community Church.

Several police vehicles were also at the scene as detectives investigated.

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No one was in custody in the shooting as of the 5 a.m. hour Tuesday.