A 16-year-old boy was shot and killed yesterday during what may have been a push-in robbery or burglary in Southwest Philadelphia, police said.

Investigators were trying to determine if the youth, not immediately identified, was a thief or an innocent victim.

The boy did not live at the rowhouse on the 5900 block of Greenway Avenue where the shooting took place about 11:45 a.m., police said. The teen, shot once in the chest, died at the Hospital of the University of Pennsylvania at 12:34 p.m.

Hours after the slaying, the street remained closed by yellow crime scene tape and investigators dusted a bicycle around the corner on Salford Street for fingerprints.

Residents said the youth was known as "Little Wayne" in the neighborhood. They expressed shock at the possibility that he was involved in a robbery.

"He was a quiet kid, didn't say much," said Caswell McFarland, sitting in a lawn chair at the corner.

Police, in the meantime, were expected to charge one of three men wounded in a West Philadelphia gun battle with the murder of a fourth during the same shoot-out.

Detectives said an argument, the nature of which was not clear, sparked the gunfight Thursday afternoon under the Market-Frankford El at 52d Street.

The slain man was identified as Wayne Bell, 21, of the 200 block of North Wilton Street in West Philadelphia.

Court records show that Bell was sentenced to 11/2 to 3 years in prison in June 2004 after pleading guilty to drug and conspiracy charges.

Bell was the city's 143d homicide victim of the year.

Police yesterday also identified the 142d victim. He was Anthony Edwards, 49, of the 7900 block of Cedarbrook Avenue in Cedarbrook.

Edwards was shot in the chest about 12:50 p.m. Thursday on the 7700 block of Ogontz Avenue and died at 2:24 p.m. at Einstein Hospital. Detectives were seeking a motive for the shooting.

Court records show that Edwards was sentenced to one year of probation on drug charges in October 2005 for a 2002 arrest.