This is my advice for biting, and it can be applied to other undesirable behaviours too.

First, Observe - is there a time when this happens more? Is it a response to something or is it just for attention? Does something happen that causes the behaviour? I have found that writing this down helps identify patterns. If there is a pattern, you can use that to limit or eliminate the trigger. Next, Shadow. Be right there whenever the child is in close proximity to the other children. You can stop it from happening or at least react immediately. Third, Limit interaction and redirect. Obviously, you should say something but keep it short, like just "no" so that the attention can be focused on the child who is hurt. Lastly, Separate. When you are busy, (like making lunch,) keep that child away from the others with gates or in a high chair. Give them something to do "away" from the action until you can be right there again.

The child in question here is exactly at the age where biting is considered normal. Not acceptable, of course, but understandable. Toddlers lack empathy. They do not understand that other people have feelings too and their actions have consequences. They also lack communication skills. They can't express in words their wants and frustrations, so they may act out. Also keep in mind that the more often your response to the biting is a lot of attention then the longer it will likely go on for. Good luck!