It happened around 11:00 p.m. Monday in the 800 block of S. 58th Street in Southwest Philadelphia.
Police say a man and his sister came home and were confronted by three masked men in the living room, all armed with semi-automatic handguns.
Inside, the man's 15-year-old nephew was bound with electrical wire.
The suspects forced the man to open a safe in the closet, then stole $25,000 in cash.
The bandits left and the victims were able to contact 911.
