A 4-year-old boy visiting his grandmother in Southwest Philadelphia died this afternoon after being shot in the throat, police said.

The shooting happened inside the grandmother's home on the 1900 block of South Salford Street, a typical block in this part of the city, with a narrow roadway and rowhouses on both sides. The boy, whose name was not released, lives with his parents, police said.

Police said shortly before 5 p.m. the boy's grandmother and great-grandmother, who also lives in the home, heard gunfire and found the boy on a second-floor bedroom.

The boy was taken to the Children's Hospital of Philadelphia, where he was declared dead about 5:30 p.m.

Homicide detectives tonight declined to speculate on who owned the firearm or how the boy got a hold of it, saying their investigation had just begun.

Neighbors said the child, who they identified as Deshawn Boyd, attended pre-school at Bright Side Academy.

Uniformed police officers and detectives this evening were inside the home - a two-story row with narrow porch and and bay window upstairs - searching for clues as to what happened.

They reported finding the handgun but not its magazine. At one point, a Fire Department ladder unit was brought in to search area roofs for the magazine.