Watch for situations where two children might want the same toy and step in first to distract them. Children in this situation need close adult supervision, especially if they are known to bite. Keep him with an adult for a while. The child needs you to understand his feelings and start teaching him to manage them differently. This takes a long time to learn.
Feelings are very hard for young children to control.
Often it is the youngest child in the family who bites. The older children seem stronger and more able to get what they want and the youngest feels small and powerless. The same can happen in groups. The child can then discover that biting is a way of getting some power in the situation. The first step is to try to make sure that the child's needs are protected so she doesn't need to bite.