Gunshot wounds put an average of 8,300 U.S. kids into the hospital every year, according to a new analysis released Monday.

​Close to half of them were shot on purpose and another 40 percent were shot accidentally, the researchers reported. Six percent of those who made it to the hospital died, the team at Johns Hopkins University School of Medicine reported.

The 30-page report examines active shooter incidents from 2000 to 2013 and suspects in 63 cases, finding suspects showed signs before they attacked but law enforcement wasn't notified in more than half the cases until it was too late.

Forty percent of suspects purchased a firearm or multiple guns legally for the sole purpose of an attack. Another 35 percent already legally owned a gun before planning an attack, meaning 75 percent of active shooter incidents reviewed by the FBI legally owned the gun they used in the attack. 

The remaining suspects stole, borrowed or purchased a weapon illegally. 
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The FBI could only verify that 25 percent of the gunmen examined in the study had any type of mental illness diagnoses, including disorders affecting mood, anxiety and personality.