We just saw a pigeon lying on a small wall near within our community building area. Its one wing seemed broken and it could not move. We called the security people but they said they can’t handle it and suggested us to wait until it flies off.
I’m not sure how it can fly off when it does not have a wing! We kept some water near it (in a small container).
You can take it to a vet. They may be able to do something. Might charge you for it, though. If your conscience clears it, you may do what someone else has said.
If they crash against a window, they probably will break every single bone and bleed to death. From the outside, you think they are OK, but it is dead man walking.