Lo biting classmates and me

My lo recently had been going around to bite his classmates. I checked with the sch, there was nothing which trigger him. He just went over and bite. What should I do to prevent it? He just bite me and I scolded him, he cried out loudly and hide under the table. But when we called him to come out, he will come out. But does it normal for toddler to hide under the table? Btw, he is 19 months TIA