The largest portion of gun deaths for young people and juveniles from ages 15-19 resulted from intentional homicides. Knowing this is startling, not least because the perpetrators were likely just as old as the victims.
Gun possession for juveniles is obviously illegal, as one must be at least 21 to obtain a gun in most, if not all, states. For juveniles age 15, gun possession is absolutely illegal, and likely can only arise thanks to the youth's association either with those who can obtain a gun, and then give it to the youth without reservations, or because they know other youths who can help them to obtain a gun. The gun deaths caused by these illegally held weapons could likely be brought down, if only there were a way to ensure that minors were not able to access illegal guns as easily.
The Youth Crime Gun Interdiction Initiative of the late 1990's was an attempt to do just this by the Bureau of Alcohol, Tobacco, Firearms and Explosives. It found such startling information as the fact that one out of 10 guns recovered after use in a crime by the police actually came from someone 17 or younger. The guns were illegally in the possession of these individuals, most of the time, but they were likely obtained legally, somehow, or stolen.
The unfortunate element of so many teen-caused gun deaths is that the teens in possession of the gun were likely to obtain a gun, if they truly wanted it. There are so many ways for any given individual to obtain a gun, even under age, including stealing it from someone else whom the minor knows has a gun. Sometimes, minors will find guns while breaking into houses without having meant to look for them, and will simply take them, often leading to unfortunate gun deaths.
The problem for determining exactly how much interaction there is between juveniles and guns is the classic problem of tracking illegal guns, in general: there's no real way to do it, unless the individual is caught while in possession of the gun.
Juveniles are often not caught until they've already caused one or more gun deaths with their illegally owned weapons, and even then many get away. It is the quintessential flaw of gang violence involving minors; it occurs, but little can be done without catching the gang members and making sure that the they are no longer in possession of guns illegally.
This is demonstrated aptly by statistics like those gathered by the San Diego Association of Governments, which sought information about crime from law enforcement agencies all across America. Their report cited that in 2005, 15% of all arrests were of juveniles, but at the same time, one in three weapons offense arrests were for juveniles.
These statistics are mildly skewed, as individuals are recorded for the worst crime they committed; for instance, a juvenile who caused a gun death would be charged with manslaughter or homicide, as appropriate, instead of gun possession. But the fact remains that if minors want to arm themselves with guns, they find it all too easy to do so.