give them lots of room, if the brooder light isn't red change it to red, chciks are going to be curious, they will peck a little at each other, but if it gets really bad if any blood shows get that bird out of there, chickens go crazy when they see blood, little nasty cannibals, another thing quit watching them so close LOL! i know it's hard, i've been there
One is a Buff Orpington (she does most of the pecking). And the other two, so far, are a mix of Buff Orp and Bantam Brahma. The 2 Orp/Brahmas are doing it to each other. And the Buff Orp just gets them both when she can. It doesn't seem like they're trying to be mean. But idunnoo.
if it is just one or two, take a pair of finger nail clippers and clip a little of the top beak off (just a little) and that may stop it from pecking the others, i had one in the batch before this last one that i had to do it to as a last thing to try, for i had put the ones that were pecking in a 2nd brooder and he just kept pecking the ones i put in there with him and when i clipped his beak he still tried to but could not hurt them, and he stopped and it grows back very fast.
I wouldn't clip beaks before I changed the light. When the light is too bright it encourages pecking/picking at each other. We used red for years, right now I"m trying a bug light. It seems to be working, they were starting to peck a bunch, and I haven't seen it now. I am looking for a study for which color does best.