How to get a small bird out of a window?

Okay, so this bird flew into my window, and has a huge cut on it's wing and body. The thing now can't fly and is stuck high up in the window on a ledge. I can't stand seeing this bird in pain, and animal control doesn't come for something like this because their funding got cut. So how can I help it? I have taken care of wild birds before and I know a wildlife rehabilitation person, but how do I get it out of the window? If I open it to reach it, the bird will fall out.