How to handle very aggressive neighbor dog?

I want to preface this by saying I don't hate/fear all pitbulls, or even pitbulls more than other breeds. It just happens that this dog has a very strong resemblance to a pitbull, and I'm pretty decent at correctly iding them.

Our house is back from the road several hundred feet. We have a long driveway. Our neighbors on both sides are much closer to the road. My son started school this year and most of the time someone is with him walking up and down the driveway, I have a toddler so there have been a couple times he's gotten off the bus and I just couldn't get out the door until he was almost all the way down it. We usually enjoy these driveway walks, I usually leash our good sized dog and bring him along.

The neighbor furthest from the driveway has a small front yard that occasionally has 3 med/large dogs in it. Their yard/fence is probably 40ish feet from our driveway. We never really paid attention to the dogs until this summer when I was keeping my nephew and working in the front yard. Nephew (4) was telling me we needed to move the house closer to the road and ran up to about even with their yard to say I should be there. No sooner was nephew in sight of their yard than that dog ran at the fence, went under it like it wasn't there and after the boy snarling and barking.

My heart dropped, no way could I make it in time. I was running toward him, he was running toward me, but that dog was going to get him. Luckily the dog was on a chain, but the chain did extend into our yard. This was in July.

Tonight my parents were outside, and this dog hit the fence and went under and he had no chain. He was snarling, and growling. My mom and dad walked backwards until they were trapped against the house, and at some point mom called me, yelling at dad to move, and yelling for me to bring the gun, and ... It was not pleasant. I left the kids inside. My dad had a big stick but this dog was not baking off. When I came around he skittered away far enough for us all to get inside, and then lost interest.

I called the cops. They came out, spoke to my parents and then the neighbors. Neighbors showed cop a broken chain and cop said to get a better chain. That's it. My mom's shoes came off while she was baking away from the dog(flip flops) and she was scared to go find them. We're worried about walking to the end of the driveway. We're worried about our kids when we're outside. We have small pistols, and some good walking sticks, but I'm no confident I'd be quick or accurate enough with either option to prevent an attack. My kids will run even if I tell them not to, they just don't know better.

Is there anything else we can do?