Do you have any idea how old the babies are?
What type of diet are they on?
What State do you live in?
We do feed KMR which is kitten milk replacer. http://ratfanclub.org/orphans.html The problem is releasing them. Since Rats are prolific breeders and can over run an area is the big problem. The best solution would be to turne them over to a Wildlife rehabilitation center where they can continue to care for them and then properly release when it is time. They may separate the males and females and may even spay or neuter them so they do not over populate an area where released.
This is a link with all the Wildlife Rehabilitators in California. They are sanctioned by the Fish and Game Commission who regulates the wildlfe and their care. http://www.dfg.ca.gov/wildlife/WIL/rehab/facilities.html
This would be the best thing for the Rats to be sure that they get the best chance for life whether it be in the wild or to teach about Wildlife at the rescues.
As far as handling them, using the proper hand cleaning and sanitation is the best way of protecting yourself. There is always a chance of parasites when dealing with wildlife, so be sure to clean with bleach water if the pass stool and you have to clean an area.