10 Week Old Puppy Snarls & Snaps at faces

[blangett]

We adopted a puppy from a dog rescue organization. We have only had her for four days and she frequently snaps at my 9 year old son in the face when he is holding her or carrying her to go outside (trying to poddy train her and take her to the same spot daily.) She has snapped at my face while I was laying down playing with her and her leash got stuck under my head. She snapped at my husband when he was trying to pick her up to remove her from our older dog who felt she was being a nusiance. I have no idea what I should do to correct her behavior without doing any mental damage to make her more aggressive. So far we have just being yelling no really loud at her and when she snapped at my husband he did a light tap on the nose and said no. I have no idea what to do, I have never seen this behavior in a puppy this age. I would appreciate any help I can get. My son has waited 3 years to have his own dog he can teach agility training and I am really worried.