HELP! my duckling got trampled by the other ducks!?

The poor little things in really bad shape, he's severly twisted/ dislocated/ broken his neck....he can thrash it around still but at horrid angles, and it looks like his left leg is broken or sprained to as when i rescued him it was just out behind him. hes 3wks old. Am i just being cruel n should euthanise him asap? i just keep wondering whether theres a poss that they're only dislocated n could b fixed!