You can use Vetericyn, saline, or Hibiclens chlorhexidene weakened 1/2 with water. Then coat the wound with plain Neosporin or triple antibiotic ointment after cleaning twice a day. Trim any feathers back that are getting into the wound. Do not use BluKote which is only for minor wounds. Leave it open and place her on a clean towel. That looks like her back, but a picture farther away may help us see the location. Is she able to stand and walk? Can you offer some sugar water or electrolytes up to her beak for shock? When she is drinking, offer moistened chicken feed and scrambled egg. Her wound may close up in a few weeks, but hopefully, she has not had any internal injuries. Watch for signs of infection (pus, reddened swelling around edges, bad odor.) Let us know how she is doing. Are the other chickens locked up and safe?