If possible, have the child who was aggressive aid the other child. Please get a warm, wet washcloth for Mary. In some cases, you will need to remove the child who was aggressive to another part of the room and allow the child to calm down before any positive behavior will be possible. Examine your home for potential sources of frustration and accidental anger. Anger grows out of frustration.
Aggression grows out of powerlessness.
You can reduce aggression by paying attention to the environment you create and by teaching children acceptable ways to achieve their goals.