I'm sorry... Train your kids!!!

When I had young kids (they survived, grew up , and moved out) There was no secret as to where my guns were or what they were capable of.
I showed them where they were so they wouldn't find them accidentally, I took the kids out to my range to watch as I shot and hear that BIG noise!
They were taught not to play with them or go near them, and they understood!
Never once had a problem.

I would hide or lock them up if there were a bunch of kids over playing, as we were that place the kids liked to go. Mostly just had to lock the bedroom door.

If you get broken into and you cant retrieve your gun in time to protect your family, then what's the point?