We have two baby bunnies living in our front yard. One of them is injured. I saw it today dragging it's hind legs behind him as it hopped along to the garden. It's eyes are open, ears are up. Clearly this bunny is injured. Sibling is fine.

Worried the bunny will get hurt by another animal, car or something else. What can we do?

A rabbit without use of its hind legs is not going to survive very long in the wild. You can either let nature take its course, or take the rabbit to a licensed wildlife rehabilitator so that it can be humanely euthanized. There are several in Lake County. You can find them at: http://web.extension.illinois.edu/wildlife/professionals.cfm Scroll to the bottom of that page and type in Lake County for the list of rehabbers in your area.