FRANKLIN, Pa. (October 9, 2012)--A 13-year-old boy who shot his grandparents to death in their Pennsylvania home has been charged as an adult, state police said.

Troopers from the Franklin barracks announced the charges Tuesday against Zachary James Proper, of Oil City, but provided few additional details.

Police say Proper shot his grandmother, Dorothy Fross, and step-grandfather, George Fross, at around 4 p.m. Sunday at their home in Sandycreek Township, about 65 miles north of Pittsburgh.

Police did not immediately say how they linked the boy to the killings.

A criminal complaint was not immediately available.