Dr. John Leventhal and his team at the Yale School of Medicine in New Haven, Conn., studied children and adolescents age 20 and younger at the time of admission to the hospital in 2009.
In that year, 7,391 U.S. hospitalizations occurred in this age group because of firearm injuries, and 453 died while in the hospital.
Most of these hospitalizations were due to assaults -- 4,559 -- but in children age 10 and younger, 75 percent of the almost 400 hospitalizations were due to unintentional or accidental injuries.
The study, published in the journal Pediatrics, found 52 percent of the gunshot injuries were due to open wounds, 50 percent were due to fractures and 4 percent were due to internal injuries of the thorax, abdomen or pelvis.
Traumatic brain injuries occurred most often in children age 5 and younger. These children often require extensive follow-up treatment including rehabilitation, home healthcare, hospital readmission from delayed effects of the injury and mental health or social services.
"These data highlight the toll of gun-related injuries that extends beyond high-profile cases, and those children and adolescents who die before being hospitalized," Leventhal said in a statement.