I doubt the pecking will stop without separation at this point. Maybe blu-kote will help a bit... It depends on how much blood there is, how bad the wounds are, and how serious your birds have become about the pecking. Plus if the wounds are bad enough, you won't want to apply blu-kote, because it will be harder for you to tell how it's healing. But that's mainly an issue with deep bite wounds and gashes.
It's hard to say without knowing the cause in the first place. You did mention that it looked like the vent on one chicken was open, like there was an egg or something in there right? I don't remember, is anybody laying? Could someone be egg bound? Sometimes chickens that are egg bound will peck at their own vents. If that happens, and they draw blood, that's basically an invitation for all the others to peck at it. And then maybe that started a habit of vent pecking.