What should i do about this??

We live in a pretty upscale neighborhood but the house across the street from us i think is running a drug thing. They always have vans and police over there. They always have people that dont look very nice over there constantly. This one man went up to my son and niece and asked them for 50 dollars and said that if they wanted they could come "have fun" with him. Luckily my 19 year old neighbor was walking along and came up to him and he left. I called the police but they dont seem to be doing anything. I dont know what else to do?