Updated: 1/13/11 10:43 a.m.

CHICAGO (CBS) – Police are looking for the person who shot and killed a 15-year-old boy at a bus stop in the Woodlawn neighborhood.

The boy — identified by the Cook County Medical Examiner’s office as Shonelle Gregory, 15, was shot about 6:45 p.m. in the 500 block of East 63rd Street, said police News Affairs Officer Veejay Zala.

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Police said the boy and two other people were waiting for a westbound 63rd Street bus, when the gunman walked up and asked everyone if another bus was coming. He then walked behind the bus shelter, pulled a silver handgun and shot Gregory once, police said.

The boy staggered to a nearby trash can, where the gunman shot him three more times in the back, police said. Gregory was dead on the scene when ambulances arrived.

Nobody else was injured, police said.

An autopsy on Gregory, of the 5200 block of South Calumet Avenue, is scheduled for Thursday, the medical examiner’s office said.

Calumet Area detectives are investigating the shooting as possibly gang-related, police said. The victim was allegedly a known gang member, police said.

Nobody was in custody as of Thursday morning.

The Sun-Times Media Wire contributed to this report.