Prince William County Police say the shooting occurred Friday around 10:45 a.m. in Haymarket, about 37 miles (60 kilometers) west of Washington.
No officers were injured.
Police responded to a call about a possible hostage situation, and were told that a person with a bomb strapped to his chest was holding a family member hostage. When police arrived, they say the 15-year-old was brandishing a crowbar and walking toward them.
Police say an officer then shot the boy, who died at the scene.
Police spokesman Nathaniel Probus had no information on the races of either the boy who died or the officer who shot him. The investigation is ongoing.