Here's a great site with some pics of some BABY rats. YOu can even try to determine the age with these pics. You're son sounds great. Ususally people wouldn't care about rats. http://ratgrowth.homestead.com/index.html
These are domestic rats, but they should be about the same. You guys could have river rats. They look more round and aren't as long as rats tend to be.
Search for some orphan rats sites. There's all sorts of places with instructions on care for baby rats.
Be sure to cover them with bedding, feed them non-dairy milk (soy baby formula works best), and....well, when my rat had babies she had to help them poop. If you want to try just gently massage the baby's tummy above the poo hole under their tail. If a little brown stuff comes out, just wip it away. Of course the babes might be poopin on their own now!
Ask if you have questions!
Lila
