The juvenile girl was handling a firearm at a home in the 4900 block of Glassmanor Drive when it discharged, striking the teenage boy at around 6:00 p.m. on Jan. 26, Prince George's County Police said.
He was taken to a hospital and pronounced dead a short time later.
Detectives believe the shooting was an accident and are continuing their investigation.
Click here to follow Daily Voice West Chester and receive free news updates.