There's a "natural instinct" for some flocking birds to peck at, or flat out kill, any member of the flock that is perceived as injured or otherwise "different".
When I was raising baby chicks we would put little red circles with crayon on boards tied to the side of their incubator so they could exercise this annoying habit, without pecking their siblings to death.
You should remove the afflicted bird/s immediately & isolate them 'till wounds have had a chance to heal; more importantly 'till any "spot" or other abnormality or discoloration has disappeared.
... and take a couple boards (or even a cardboard box) & put little 1/2" red spots on them so the rest of the critters can peck themselves dizzy in the meanwhile.
