Found an injured duck.. what to do?

We were out for a walk and feeding ducks (bird seed) and this duck comes right up to me clearly starving. He can barely walk, his leg was completely broken. He struggled to even move. You could tell how scared and in pain he was.

There’s no wildlife rescue places near us or really anywhere around here. What do we do? I don’t want to leave him because of how hurt he is. It also looked like his side was messed up, like he got attacked. All the other ducks seemed to have isolated him. He was even having trouble diving for fish in the water. We watched him for a few hours probably for 2-3 days.

He’s the only one that comes up to us even when we have food. Is there anyone we can call since there’s no wildlife places? 😩😩😩