I found this article that addresses this #toddler behavior of agression, hitting and biting. It talks about why it happens and what to do when it happens…
Shocking as it may be to you (and onlookers), aggressive behavior is a normal part of your toddler’s development. Still-emerging language skills, a fierce desire to become independent, and undeveloped impulse control make children this age prime candidates for getting physical.
Source: Baby Center