An 18-year-old man riding a bike was shot to death Wednesday evening in the Mantua section of West Philadelphia, police said.

Shortly after 6:30 p.m., the teen was seen riding a bicycle west in the 3500 block of Wallace Street when he collapsed, said Chief Inspector Scott Small. Another man was then seen taking the victim's bike and riding away east on Wallace.

Police responding to the shooting took the teen, who was shot in his right shoulder, to Penn Presbyterian Medical Center, where he was pronounced dead at 6:49 p.m.

Small said police received preliminary information that the victim may have been involved in an argument over gambling. It was unknown if the man who took the bike was involved in the shooting.

Police found 11 shell casings at the scene.

- Robert Moran