Biting help- 18 months old.

Lately our son's been getting more and more violent, especially with biting.

He mainly would try to get your hand when you went to grab his hand to redirect him or move directions with him, but now it's happening almost every time he gets upset. This morning, after he finished his food and was wanting out, I went to wipe his hands and face down and he squirmed like most kids do but he grabbed my hand through the rag and went to snap it like you'd see a dog do. So knee-jerk and aggressive it made me jump back. Then when I tried buckling him into his car seat later he got angry and it was like watching a dog again. He grabbed my hand and snapped his head over so fast but luckily missed and bit the side of his arm instead. You could see it literally took him a second to realize it was himself that's how angry this was. And finally just now he woke up crying in his crib so I went in to try to console him and just playfully jiggled his hand to try to snap him back into it since he was screaming so hard he didn't notice me come in, and he went for my fingers. Ended up hitting his mouth on the crib because once again he tried to snap down and bite my hand.

I'm literally petrified of it, I can't stop crying. What am I supposed to do? What if he gets a kid at school like that or a grandparent?