That's really scary that your kids were in the yard. Glad you got it.
We had one about that big in our yard about two weeks ago. The dog would not stop barking and I went outside to see what was going on. He was standing over something barking at the ground. First thing I heard, over his barking, was what sounded like a really loud Mexican cucaracha band playing and knew it had to be a rattle snake.
I call of the dog and run in to get hubby and tell him to get his gun. Well, he can't find his key to his gun cabinet, then his shells are in his truck and can't find his key to that, then he needs to find his shoes. By the time we got back outside I was sure the snake would be gone but he was still crawling off when DH took aim and hit it from the porch with me just shining a light out into the yard onto it. I told DH that we lived in the country now and that he was to keep the gun loaded and accessible at all times.
By the way, he is from Odessa - name is John Wagner, his mother still lives there.