Hens gang up on one hen-advice please?

Hi,

We have some 5 California Rocks/random whites and 4 Red Sexlinks. Well the reds seem to gang up on one white hen, to the point of pecking her bloody. She sits in a corner. We have separated her twice [she is currently separated now] and I am applying triple antibiotic cream to her wounds.  Otherwise, she is very friendly although rather ticked off.

What can I do to prevent this in the future? We are honestly just thinking of giving away the reds [even though they are fantastic layers] and getting some new chicks and starting from 'scratch.'

Any comments would be greatly appreciated!

Thanks,

Brenda

Thank you both for the excellent advice. I will do that, observe to see who starts it and get some BlueKote for my wounded hen.

Just to follow up, but I did Bluekote the pecked one, and she is doing well but she is still quarantined because every time I put her in the pen with the others, the 4 Reds wait a few minutes and then literally JUMP her, pecking and squawking, on her back, etc. I have to jump in like a crazy person and shoo everyone away to pull her out. So, I think the Reds need to go.  Incidentally, another white hen just died last week but looked perfectly normal up until her death. 

Oh, and yes I double-checked the size and they are fine in that regard, with plenty of hiding and roosting spots.

Thanks everyone!

Update April 7-Bluey [as we have now named the victim] roams freely right now, outside of the hen house while her attackers, the 4 Reds, remain inside. I plan on getting rid of them as soon as I can get some chicks but I never make it to Farm and Fleet early enough! She is very docile, and definitely on the mend. Too bad chickens poop at random, or I would bring her in the house. She is better than a cat!