I found an injured baby bunny, what do?

Contact a local Wildlife rescuer. Search for local ones and ring them up. If not, try and do your best by yourselves. Research about this situation and see what Information you collect. It all depends how bad its legs are broken and where it is bleeding. Usually putting its legs and straight as you can and wrapping them up snug so its doesn't shift or change, sort of like a cast, can do good until you get it help. If you keep caring for it for a while and making sure it doesn't use its legs, and that its legs are wrapped up tight, it could heal. But that should be the last thing you do because it could always heal the wrong way. Wildlife rescuers don't cost any money, they do it for free and they are experienced in what they do. Please call one ASAP. Stop the bleeding with pressure, then bandage the spot. Also make sure it doesn't have internal bleeding, which only a vet or rescuer could know.

The rabbit will not live long - no way can you keep it long enough to try and fix the legs and even if it does, it will not survive well and be easy prey. Best to put it down if you have time - the rabbit may not live for more then a day or two anyway.

Take to the nearest vet or animal ER asap! But don't stress out or the rabbit will as well, try to calm the rabbit by providing food and or leave it alone...try to prevent the injury from worsening and wear gloves if you touch the rabbit in case of diseases.

Put it outside or take it to a wild life center so it can be put down. Vets legaly can't touch wild animals and can't do anything for it and its illegal for you to even have it

If you can't shoot him, you'll have to drown him. The poor little thing. Even if his legs weren't broken, he might just die of loneliness if you keep him.