The problem with the phrase "just an accident" is that it is dismissive of further analysis which might lead to a solution that prevents this happening in the future. It implies that, as a accident, it was unavoidable.
Of course it was an ACCIDENT. But it wasn't just an accident. It was much more than just an accident. It was tragically bad judgement on the part of the adults who were supposed to be in charge. And it should lead to policy changes for all shooting ranges, enforced by the feds if necessary.
OMG! Gun control!