I have a 4 almost 5 year old that says the same thing. He has only been scared by one man that refused to leave him alone until we moved. My son is very intelligent, he tells me what the people look like, if they are good or bad, and if they are nice to him. Coming from a family that sees things, I only have the gift to know when they are present and if they are good or bad. At first I was scared because I didn't know how to help him because I can not see them. I just listen to what he says and then I try to look up information on the people he sees. So far he has only seen 5/6 of them and one of them happens to be his great grandmother from my husbands side that died when my husband was 6 and he is now 28. Don't be worried about what he sees, Just try and listen to what he says and be there for him. Most children do outgrow it, lord knows I hope my son does. The crazy thing is that my 3 year old does not see them, only my oldest child.