Since the Parkland shoot from my quick count on this link about 3 dozen teens have been killed by firearms. From a quick skimming of the source articles the vast majority are homicides and not killed by an AR15.
If you are a 17yr old black girl from Youngstown shot in the back while sitting in a parked car in Cleveland you are not likely to get national media attention.
http://www.gunviolencearchive.org/reports/teens-injured-killed