BERWYN, Pa. (January 22, 2013)--Police are investigating the strong-arm robbery of Girl Scouts who were selling cookies at a Pennsylvania supermarket.

The theft happened at around 5 p.m. Sunday at a Pathmark store in Tredyffrin Township, Pa., outside of Philadelphia.

The robber reached into a box containing the scouts' cookie money and grabbed $20 before the girls closed the lid.

He fled to the back of the building and then drove off.