I'm not aware of any such laws, but if there isn't, there should be. I think that it's our responsibility as responsible gun owners to help ensure our children aren't able to carry out some of the things we've recently seen in the news.
The fact that the mother of Adam Whatshisface didn't do a better job of keeping firearms from her son is beyond me. She obviously knew he was suffering from some serious mental issues, so it's beyond me why she wouldn't keep them properly secured.
I've seen other parents in similar situations act just as irresponsibility as she did. Then you have those other parents who are positive their children could not and would not do such a thing. It's simply not worth risking, in my humble opinion.